What are whiteheads

Whiteheads are also called pimples with closed plugged hair follicles or sebaceous gland pores, whiteheads are the mildest forms of acne (comedonal acne) and are generally treatable with proper skincare habits and a topical whitehead treatment. Whiteheads are small, white, raised bumps on the skin (see Figure 1). Whiteheads form when oil and skin collect in the sebaceous gland pores. Whiteheads are also known as closed comedones and pimples. In whiteheads the sebaceous gland pore is covered by a thin layer of skin that traps the plug beneath the skin surface. As the plug is not exposed to air it remains white or sometimes a yellowish color (the natural color of oil and dead skin cells), which is why it’s called a “whitehead.”

Whiteheads occur with acne, often on the face, chest and back.

If you have acne, you’re certainly not alone. An estimated 85% of US adolescents and young adults have acne, making it one of the most common skin conditions in the nation. Acne occurs after sebum, an oil produced by sebaceous glands in the skin, combines with dead cells that are shed from a person’s pore. This results in an enlarged, closed pore called a comedo. Comedones create a perfect breeding ground for a bacterium called Propionibacterium acnes (P. acnes). If the walls of the pore break down, an inflammatory response is triggered, leading to pimples or, if more severe, cysts.

The sebaceous gland is integral to the structure and function of the skin, providing 90% of its surface lipids ¹. While much of the focus relating to the sebaceous gland comes from its central role in acne vulgaris, the sebaceous gland is special in at least two ways. Firstly, the product of this gland is synthesized via holocrine secretion, a unique method characterized by the purposeful self-destruction of its primary cellular unit, the sebocyte. Secondly, despite being of epithelial origin and possessing numerous hormone receptors, sebocytes engage in lipid synthesis and metabolism, a job normally reserved for adipocytes. Thus, the sebaceous gland can be considered both a hormonal target as well as an endocrine organ.

Figure 1. Whiteheads

Figure 2. Skin anatomy

What causes whiteheads

Acne, also known as acne vulgaris, is characterized by comedone (blackheads and whiteheads), pimples, and deeper lumps (cysts or nodules) that typically occur on the face, neck, chest, back, shoulders, and even the upper arms. About 85% of all people have acne at some point in their lives. Even though acne usually begins during puberty, anyone can have it at any stage of life.

Virtually every adolescent has a few “acne”, however, about 15% of the adolescent population have sufficient problems to seek treatment. In most patients, but not all, the acne clears up by the late teens or early 20s. More severe acne tends to last longer. A group of patients have persistent acne lasting up to the age of 30 to 40 years, and sometimes beyond. Patients with persistent acne often have a family history of persistent acne. Acne may scar – most of the time this is preventable by using the correct treatment given in a timely fashion.

The cause of acne is unknown, but factors that can contribute to the cause of acne include heredity/genetics, hormones, menstruation, and emotional stress. Acne appears on the skin when overactive sebaceous oil glands produce too much oil and the pores in the skin get plugged. Propionibacterium acnes is a gram-positive human skin commensal (present on everyone’s skin) that prefers anaerobic growth conditions and is involved in the pathogenesis of acne ². The bacterium Propionibacterium acnes multiplies in the excess of oil in the blocked pores and leads to inflammation on the skin. Eating greasy foods such as french fries and pizza does not directly cause acne, but some people feel their acne worsens after eating certain foods.

The cause of acne has four major features (see Figure 3 below)

1. Androgen-induced seborrhea (excess grease)
   • The more sebum (grease) the greater degree of acne
   • Sebum is produced by the pilosebaceous glands, which are predominantly found on the face, back and chest
   • Evidence suggests that in most patients the seborrhea is due to increased response of the sebaceous glands to normal levels of plasma androgens
2. Comedone formation (blackheads, whiteheads and microcomedones), which is known as comedogenesis
   • Is due to an abnormal proliferation and differentiation of ductal keratinocytes
   • It is controlled, in part, by androgens – male sex hormone 5-testosterone (DHT)
   • In pre-pubertal subjects comedones are seen early and they precede the development of inflammatory lesions
3. Colonization of the pilosebaceous duct with Propionibacterium acnes (P. acnes)
   • Is a later stage in the development of acne lesions (especially inflammatory lesions)
   • The seborrhea (excess grease) and comedone formation alter the ductal micro environment, which results in colonization of the duct
   • Propionibacterium acnes is the most important organism
4. Production of inflammation. This is a complex process involving an interaction between:
   • Biological changes occurring in the duct as a result of comedone formation and Propionibacterium acnes colonization of the duct
   • And the patients cellular (especially lymphocytes) response within the dermis, which responds to pro-inflammatory cytokines spreading from the duct to the dermis

Figure 3. Causes of whiteheads

Footnote: P. acnes = Propionibacterium acnes

Factors which can/might modify acne

• Hormonal factors
  • About 70% of females will notice an aggravation of the acne just before or in the first few days of the period
  • Polycystic Ovarian Syndrome (PCOS) / other endocrinological disorders
• UV light can benefit acne
• Stress
  • This is a controversial issue – there is some evidence that stress makes acne worse but data to support this view is limited
  • Stress may manifest itself as acne excoriee, where patients, usually females, habitually scratch the spots the moment they appear
• Diet – although the evidence for a link between diet and acne is not strong, some people with acne have reported improvement in their skin when they
  • Follow a low-glycaemic index diet, which can be achieved by:
  • Increasing the consumption of whole grains, fresh fruits and vegetables, fish, olive oil, garlic
  • Decreasing the consumption of high-glycaemic index foods such as sugar, biscuits, cakes, ice creams and bottled drinks
• Cosmetics
  • Caused by oil-based cosmetics
  • Pomade acne is caused by hair pomades, with comedonal and papulopustular acne on the forehead and temples
• The following drugs may cause acne:
  • Topical and oral corticosteroids
  • Anabolic steroids
  • Lithium
  • Ciclosporin
  • Iodides taken orally, which may be part of some homoeopathic therapies

What causes comedones?

Comedones arise when cells lining the sebaceous duct proliferate (cornification), and there is increased sebum production. A comedo is formed by the debris blocking the sebaceous duct and hair follicle. It is now known that comedones also involve inflammation (see causes of acne).

The development of comedones may involve the following factors:

• Excessive activity of the male sex hormone 5-testosterone (DHT) within skin cells
• Reduced linoleate (the salt of the essential fatty acid, linoleic acid) in sebum causing more scale and reduced barrier function
• Proinflammatory cytokines (cell signalling proteins), such as Interleukin 1 (IL-1) and IL-8, produced by cells lining the follicle in response to activation of the innate immune system
• Free fatty acids made from sebum by acne bacteria
• Overhydrated skin premenstrually, from moisturisers or in humid conditions
• Contact with certain chemicals including oily pomades, isopropyl myristate, propylene glycol and some dyes in cosmetics
• Rupture of the follicle by injury such as squeezing pimples, abrasive washing, chemical peels or laser treatments
• Smoking – comedonal acne is more common in smokers than in non-smokers
• Certain dietary factors may contribute to comedonal acne, particularly milk products and high glycaemic-index foods (sugars and fats)

How to get rid of whiteheads

You should first know that treating acne is like starting a new exercise program—you won’t get results right away. Since it takes a comedo 8 weeks to mature, treatment must be continued beyond this time frame to start seeing results.

Although whiteheads can pop up overnight, there is no instantaneous cure. Even the most effective treatments take time to get rid of whiteheads, so consistent treatment is ideal and a noticeable change may not be seen until after several weeks or even a few months.

While there are hundreds of products to choose from, the following are broad classes of over-the-counter ingredients found in anti-acne products. Hopefully, these groupings will help you decide which anti-acne product is right for you.

If you have whiteheads (comedonal acne), choose oil-free cosmetics and wash twice daily with a mild soap and water. It is best to stop smoking and to have a diet that is low in sugar, fat and dairy products.

Choose “comedolytic” topical medications. These should be applied once or twice daily as a thin smear to the entire area affected. It may take several weeks to months before worthwhile improvement occurs. Treatment needs to be continued long-term (sometimes for many years).

Suitable topical agents include:

• Benzoyl peroxide
• Azelaic acid
• Salicylic acid +/- sulfur and resorcinol
• Glycolic acid
• Retinoids such as tretinoin, isotretinoin, adapalene (these require a doctor’s prescription)

Prescription oral medications for comedonal acne include:

• Hormonal therapy
• Isotretinoin

Antibiotics can also improve comedonal acne but are usually prescribed for inflammatory acne (acne vulgaris).

Surgical treatments are sometimes recommended to remove persistent comedones:

• Cryotherapy
• Electrosurgery (cautery or diathermy)
• Microdermabrasion

Benzoyl peroxide

Benzoyl peroxide is arguably the most effective ingredient in over-the-counter anti-acne products. Benzoyl peroxide is safe for adults and children and can be used in pregnancy.

Benzoyl peroxide is an antimicrobial and a comedolytic (opens clogged pores), helping to decrease the amount of P. acnes as well as slough off dead cells on the skin to allow the pores to open. Because it fights bacteria, it is a great ingredient if you have inflamed pimples. Typically, people apply benzoyl peroxide once to twice a day. It is available in prescription and non-prescription strength, ranging from 2.5% to 10% gels, lotions, creams, masks, and cleansers. Higher concentrations might not necessarily lead to better results and can actually lead to worse side effects. Benzoyl peroxide makes topical retinoids more photo-sensitive. Therefore, if you are using both ingredients, you should apply benzoyl peroxide in the morning and retinoid at night. Benzoyl peroxide can cause irritation that might make your skin red, scaly, and dry. And be aware that benzoyl peroxide can bleach clothes or hair, so plan accordingly while using this product ³.

Benzoyl peroxide has the following properties:

• Antiseptic: it reduces the number of skin surface bacteria (but it does not cause bacterial resistance and in fact can reduce bacterial resistance if this has arisen from antibiotic therapy). It also reduces the number of yeasts on the skin surface.
• Oxidizing agent: this makes it keratolytic and comedolytic (it reduces the number of comedones).
• Anti-inflammatory action.

Benzoyl peroxide is available as cream, gel, lotion and washes at concentrations of 2.5 %, 5 % and 10 %. It may be combined with other topical or oral therapy. It is especially valuable in combination with topical or oral antibiotics as it may reduce the growth of antibiotic-resistant bacteria.

Products containing benzoyl peroxide are available without a prescription. They include:

• Benoxyl™ 5%, 10% Lotion
• Benzac™ AC2.5%, 5%, 10% Gel; Wash 5%
• Brevoxyl™ 4% Cream
• Oxy™ 5 5% lotion, Oxy™ 10 10% Lotion
• PanOxyl™ 2.5%, 5%, 10% Gel, PanOxyl™ AQ 2.5%, 5%, 10% Gel

Benzoyl peroxide is also available on prescription in combination with other active agents.

• Epiduo® gel: benzoyl peroxide with adapalene, a topical retinoid
• Duac® Once Daily gel: benzoyl peroxide with clindamycin, a topical antibiotic

How to use benzoyl peroxide products

• Make sure the skin is clean and dry before applying
• Apply a thin smear to areas of skin affected by acne, initially every second night, then build up to once or twice daily as tolerated
• It can be used on the face as well as the trunk
• Be patient: acne responds very slowly to treatment. It may take several months to notice an improvement

Problems with benzoyl peroxide products

• Dryness of the treated area can be expected and is usually mild. If the skin is visibly scaly, apply a light non-oily moisturizer.
• Skin irritation is rarely severe. Occasionally, irritation means that product must be discontinued. Consider applying it less frequently.
• Contact dermatitis (red, dry, itchy skin) can be due to irritation or allergy. It can be treated with a topical steroid such as hydrocortisone cream (available at a pharmacy without a prescription).
• Rarely, serious allergic reactions to benzoyl peroxide, including anaphylaxis, have been reported.
• Bleaching of clothing. Make sure the benzoyl peroxide has completely dried before the treated skin touches clothes, towels or bedding. It is more likely to stain cotton and linen fabrics than polyester and fleece fabrics ³.

Azelaic acid

Azelaic acid is a natural material produced by a yeast that lives on normal skin, Malassezia furfur (also known as Pityrosporum ovale).

Azelaic acid is available at a concentration of 20% as Skinoren™ Cream, Acne-Derm™ Medicated Lotion and Azclear Action Medicated Lotion. An azelaic acid foam preparation was approved by the FDA and marked in the USA in July 2015.

Azelaic acid is used as a topical treatment for mild to moderate acne, and may be combined with oral antibiotics or hormonal therapy. It is useful for both comedonal acne and inflammatory acne.

Azelaic acid is:

• Antibacterial – it reduces the growth of bacteria in the follicle (Proprionibacterium acnes and Staphylococcus epidermidis)
• Keratolytic and comedolytic – it returns to normal the disordered growth of the skin cells lining the follicle
• A scavenger of free radicals – i.e. it reduces inflammation.

Azelaic acid also helps reduce pigmentation, so it’s particularly useful for darker skinned patients whose acne spots leave persistent brown marks (postinflammatory pigmentation) or who have melasma.

Azelaic acid cream may also be useful in the treatment of other skin disorders:

• Rosacea
• Lentigo maligna, a type of early melanoma. Azelaic acid is not recommended for most cases of this pre-cancerous lesion; where possible, surgery should be performed.

How is azelaic acid cream used?

Azelaic acid cream should be applied to the area affected by acne initially daily, then if tolerated building up to a generous twice-daily application after thoroughly cleansing the skin.

Acne responds slowly to treatment. Some improvement should be seen after one month of using azelaic acid cream. Further improvement should occur with maximum results after six months’ continuous use. Treatment may be continued safely for months or years if the acne remains active.

Azelaic acid cream side effects

Azelaic acid is nontoxic and is well tolerated by most subjects. However, those with very sensitive skin or who suffer from eczema, may find it irritating to apply, resulting in a mild irritant dermatitis.

Discontinue applying azelaic acid cream and seek medical advice if you develop severe:

• Redness
• Scaling
• Itching
• Burning

Azelaic acid does not result in:

• Bacterial resistance to antibiotics
• Reduction in sebum production
• Photosensitivity (easy sunburn)
• Staining of skin or clothing
• Bleaching of normal skin or clothing

Alpha hydroxy acids

Alpha hydroxy acids or AHAs are a group of organic carboxylic compounds including glycolic acid (from sugar cane), citric acid (from citrus fruit), lactic acid (from milk and pickled vegetables), malic acid (from apples) and tartaric acid (from grapes). Alpha hydroxy acids have the added benefit of reducing the appearance of acne scars by stimulating the growth of new, smoother skin.

Glycolic acid and lactic acid are often used in cosmetics to rejuvenate the skin.

Alpha hydroxy acid skin care products

There are many products with varying concentrations of various alpha hydroxy acids in differing bases. For the best results, leave-on preparations should be applied at night, if necessary twice daily. They can be alternated with other anti-ageing preparations including retinoid creams and vitamin C.

There are specific preparations for dry, normal and oily skin. Those available from medical practitioners are stronger than those at pharmacies and beauty therapists.

Don’t forget the essential skincare tip — always protect your skin from the sun.

Proactiv®, one of the most popular acne treatments in the US, uses a combination of benzoyl peroxide and glycolic acid. It consists of a three-part system: the first part consists of a cleanser that has tiny beads and benzoyl peroxide. The beads help to physically remove dead skin cells, and the benzoyl peroxide exfoliates the skin and kills bacteria. The second part consists of a toner that contains glycolic acid, and it works to physically exfoliate the skin, sloughing off dead cells. The third part consists of a repairing lotion that contains another dose of benzoyl peroxide, providing additional exfoliation and killing even more bacteria. Although there are other anti-inflammatories, moisturizers, and botanicals in Proactiv®, the main treatment is from the benzoyl peroxide and glycolic acid. One reason why Proactiv® works so well is that people use it twice a day, every day, even when their skin is clear.

Who should use alpha hydroxy acid treatments?

Alpha hydroxy acid preparations are recommended for those whose skin is showing signs of ageing. Fine lines, brown marks and dry spots (actinic keratoses) can improve with regular applications or peels. Glycolic acid may also prove helpful for those prone to acne. It is safe in pregnancy.

How do alpha hydroxy acid treatments work?

With time and sun exposure there is a gradual but slow-down in the rate at which old cells leave the surface of the skin and are replaced by newer cells. This results in a surface layer of dead skin cells that are responsible for the appearance of aged skin. Alpha hydroxy acids encourage the shedding of old, sun-damaged surface skin cells.

They loosen the glue-like substances that hold the surface skin cells to each other, therefore allowing the dead skin to peel off gently. The skin underneath has a fresher, healthier look with a more even colour and texture.

With high concentration and long-term use, alpha hydroxy acids may also affect the deeper layers of the skin. Collagen and elastin regenerate making fine lines less obvious.

What do alpha hydroxy acid peels involve?

Alpha hydroxy acid peels are an ideal treatment for busy people who are unable to take time off work for a deeper peel or laser resurfacing. They gently retexture the skin over a few months. The treatments are also helpful in stabilizing oily or acne-prone skin and improving skin tone.

A glycolic acid peel takes about 15–20 minutes. It is usually repeated at one to two weekly intervals as it is superficial, so recovery is rapid. The strength of each peel ranges from 20 to 70%, depending on skin sensitivity and starting gently.

The face is cleansed thoroughly, and then the peel solution is applied for three minutes. It stings mildly. The solution is then washed off.

Treated skin may be a little pink immediately after treatment. A little peeling may occur over the next few days. It can be disguised with moisturiser or normal make-up.

Salicylic acid

Salicylic acid belongs to a group of medicines known as keratolytics. Salicylic acid is used in the treatment of scaly skin diseases where the skin has become thickened, scaly and flaky. Salicylic acid helps break down clogged pores. It might also slow shedding of cells inside the pores, preventing them from getting clogged. It can cause mild stinging and skin irritation. Over-the-counter acne products are available with 0.5-2% salicylic acid. Popular products that contain salicylic acid include Oxy® and Noxzema®. This ingredient is great for those with acne consisting mainly of whiteheads and blackheads, with little or no inflammation (because salicylic acid does not have an anti-inflammatory component).

Topical preparations of salicylic acid, either alone or in combination with other medicines, can be used to treat the following common scaly skin conditions:

• Viral warts
• Psoriasis
• Seborrheic dermatitis
• Chronic atopic dermatitis
• Lichen simplex
• Ichthyosis
• Acne

How does salicylic acid work?

Salicylic acid works by softening keratin, a protein that forms part of the skin structure. This helps to loosen dry scaly skin making it easier to remove. When salicylic acid is used in combination with other medicines it takes off the upper layer of skin allowing the additional medicines to penetrate more effectively.

In acne, topical salicylic acid helps slow down shedding of the cells inside the follicles, preventing clogging. Salicylic acid also helps break down blackheads and whiteheads.

Salicylic acid preparations

Salicylic acid preparations come in many forms and strengths. Available dosage forms include cream, gel, lotion, ointment, pads, plaster, shampoo, cleanser and topical solution. Strengths of salicylic acid preparations range from 0.5% up to 30%. The form and strength chosen depends on the condition that is being treated.

Whilst many salicylic acid preparations are available from a pharmacy, some preparations are only available on a doctor’s prescription. These include preparations containing a combination of salicylic acid and topical corticosteroid, e.g. Diprosalic®.

How to use salicylic acid preparations

• It is very important that you use preparations strictly as directed on the label. Do not use more of it, do not use it more often, and do not use it for a longer time than recommended. Failing to follow instructions may lead to increased absorption through the skin and salicylic acid poisoning.
• Avoid contact with eyes and other mucous membranes, such as the mouth, inside of the nose, and genitals. Accidental application to areas should be flushed immediately with water for 15 minutes.
• Do not use on irritated skin or on any area that is infected or reddened.
• Protect areas surrounding the affected area by applying petroleum jelly around the periphery of the area to be treated.
• Unless your hands are being treated, wash them immediately after applying this medicine.

Side effects of topical salicylic acid preparations

Salicylic acid preparations are usually well tolerated. Mild stinging may occur especially on broken skin and when higher concentrations are used. Salicylic acid can irritate or burn healthy skin so it is important to keep the medicine confined to the affected area(s). Check with your doctor if you:

• experience moderate or severe skin irritation (particularly if not present before use of this medicine)
• flushing
• unusually warm skin and reddening of skin

True allergy to topical salicylic acid is rare, however serious reactions including anaphylaxis have been reported.

Salicylic acid poisoning (overdose) with topical preparations is rare. Symptoms of poisoning include confusion, diarrhoea, nausea, vomiting, dizziness, headache, rapid breathing, continuing ringing or buzzing in ears, severe drowsiness.

Precautions when using topical salicylic acid preparations

When using salicylic acid preparations do not use any of the following preparations on the affected area, unless directed to do so by your doctor.

• Alcohol containing preparations
• Any other medicated topical agents, e.g. benzoyl peroxide, topical retinoids, calcipotriol
• Abrasive soaps and cleansers
• Cosmetics or soaps that dry the skin or are designed to peel/exfoliate

Inform your doctor if you are pregnant or breast-feeding. Salicylic acid can be absorbed through the mother’s skin. The risks and benefits will need to be discussed with your doctor before using any preparations containing salicylic acid.

Salicylic acid preparations should not normally be used in children younger than 2 years. Use in young children should be monitored carefully as children are more likely to get skin irritation and the absorption through skin is greater.

Resorcinol and sulfur

Resorcinol and sulfur are typically found together in anti-acne treatments. Resorcinol helps break down hard, rough skin, making it a great way to reduce the amount of existing blackheads and whiteheads. Sulfur has been used for over 50 years for treating acne, but we really don’t know how it works. Together, resorcinol and sulfur help decrease oil buildup and are typically found in strengths of 5-8% and 2%, respectively. Clearasil® is a popular product that contains these two ingredients.

Retinoids

Topical retinoids are creams, lotions and gels containing medicine derived from Vitamin A that work in two ways: they decrease shedding of the pore to prevent formation of a comedo, and they decrease inflammation by reducing the number of P. acnes within the skin. Retinoids, therefore, treat two of the four main causes of acne, making it a very effective remedy. Prescription-only retinoids include isotretinoin, adapalene and tazarotene. While they are the most effective, you can only get them after visiting your doctor. Retinol is an over-the-counter retinoid that can be used to help manage mild acne.

Many brand-name creams containing the retinoids retinol and retinaldehyde can be obtained over the counter at pharmacies and supermarkets.

Keep in mind that topical retinoids make the skin more sensitive to sunlight by thinning the very top layer of the skin, the stratum corneum. So protect your retinoid-treated skin from the sun and other forms of external irritation.

The more potent topical retinoids available on prescription are:

• Tretinoin
• Isotretinoin
• Adapalene
• Alitretinoin.

Adapalene gel has received approval from the FDA in the USA for over-the-counter use of acne treatment in patients 12 or older (July 2016). It is also available to treat acne in combination with benzoyl peroxide.

What are topical retinoids used for?

Tretinoin, isotretinoin and adapalene are used for:

• Mild to moderately severe acne. It may take six weeks or longer before improvement occurs.
• Sun damage (photoageing). If used long term (> 6 months), they may reduce fine wrinkles, freckles, solar lentigines, solar comedones, and actinic keratoses.
• Melasma, as a component of bleaching cream.

Alitretinoin gel is used to treat Kaposi sarcoma.

How to use topical retinoids

Topical retinoid is usually applied once a day, typically at night because it breaks down when exposed to sunlight. Because topical retinoids can actually prevent acne, you should apply a pea-sized amount over the entire face and not just to individual lesions.

Follow these instructions carefully:

• Be cautious if you are using other topical acne treatments – ask your doctor if you should stop these.
• In general, a cream is less irritating than a gel. If there is a choice, start with a lower concentration product.
• Use your topical retinoid on alternate nights at first. If you have sensitive skin, wash it off after an hour or so. If it irritates, apply it less often. If it doesn’t, try every night, and if possible twice daily. In most people, the skin gradually gets used to it.
• To reduce stinging, apply it to dry skin, that is, 30 minutes or longer after washing.
• Apply a tiny amount to all the areas affected, and spread it as far as it will go.
• Don’t get it in your eyes or mouth.
• Apply sunscreen to exposed skin in the morning.
• Wear your usual make-up if you wish, and use gentle cleansers (avoid soap) and apply non-greasy moisturisers as often as required.
• If you have acne, choose oil-free cosmetics.
• If your skin goes scarlet and peels dramatically even with cautious use, the retinoid may be unsuitable for your sensitive skin.
• Tolerance to topical retinoids often develops over time.

Topical retinoids side effects

Topical retinoids can irritate the skin, especially when first used in people with sensitive skin, resulting in stinging. Excessive use results in redness, swelling, peeling and blistering in treated areas. It may cause or aggravate eczema, particularly atopic dermatitis.

By peeling off the top layer of skin, they may increase the chance of sunburn. Irritation may also be aggravated by exposure to wind or cold, use of soaps and cleansers, astringents, peeling agents and certain cosmetics.

Some people have reported a flare of acne in the first few weeks of treatment, which usually settles with continued use.

Retinoids taken by mouth may cause birth deformities. Manufacturers recommend that topical retinoids are not used in pregnancy or breastfeeding as negative animal studies are not always predictive of human response.

References

1. Hoover E, Krishnamurthy K. Physiology, Sebaceous Glands. [Updated 2018 Oct 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499819
2. Kirschbaum JO, Kligman AM. The pathogenic role of Corynebacterium acnes in acne vulgaris. Archives of Dermatology. 1963;88:832–833
3. Edwards T, Cardwell L, Patel N, Feldman SR, Title: Benzoyl Peroxide Gel Stains Synthetic Fabrics less than Cotton, Journal of the American Academy of Dermatology (2018), doi: 10.1016/j.jaad.2018.05.008