What causes sneezing

A sneeze is a sudden, forceful, uncontrolled burst of air through the nose and mouth. Sneezing is caused by irritation to the mucous membranes of the nose or throat. Sneezing is considered to be a physiological defense mechanism against nasal mucosal irritation due to allergy, infection or local pathology ¹. Sneezing can be very bothersome, but is rarely a sign of a serious problem.

Sneezing can be due to:

• Rhinitis
• Allergy to pollen (hay fever), mold, dander, dust
• Breathing in corticosteroids (from certain nose sprays)
• Common cold or the flu
• Drug withdrawal
• Triggers such as dust, air pollution, dry air, spicy foods, strong emotions, certain medicines, and powders

Unusual triggers of sneezing include sudden exposure to bright light, full stomach (snatiation reflex), sexual ideation and orgasm ². Sneezing can further be triggered by physical stimulants of the trigeminal nerve, as a result of central nervous system pathologies such as epilepsy, posterior inferior cerebellar artery syndrome or as a symptom of psychogenic pathologies ³.

Rhinitis

Rhinitis is the inflammation of the nasal mucosa causing nasal stuffiness, rhinorrhea, nasal pruritus and sneezing ⁴.

Rhinitis is a condition that typically involves nasal obstruction or congestion, runny nose or post-nasal drip, itchy nose, and/or sneezing.

There are various causes for these symptoms, although they are broadly divided into two types: allergic rhinitis (nasal symptoms related to allergy) and non-allergic rhinitis (nasal symptoms that are not related to allergy).

What are the symptoms of rhinitis?

Symptoms of rhinitis may include:

• Nasal blockage or congestion
• Sneezing
• Runny nose or postnasal drainage
• Itchy nose

Rhinitis may occur before a case of sinusitis or with sinusitis, a condition where infection or inflammation affects the sinuses. If you have facial pressure, decreased sense of smell, or a greenish-yellow nasal drainage, you may also have sinusitis. A qualified ENT (ear, nose, and throat) specialist, or otolaryngologist, can provide a thorough evaluation and appropriate treatment for your nasal/sinus condition.

What causes rhinitis?

Allergic rhinitis occurs when your body’s immune system over-responds to specific, non-infectious particles such as plant pollens, molds, dust mites, animal proteins, chemicals, foods, medicines, insect venom, and other triggers. During an allergic attack, a special antibody (fighting protein), called IgE, attaches to cells that release histamine and other chemicals in the lungs, skin, and the mucous linings of the body. These chemicals open the blood vessels and produce skin redness and swollen membranes. When this happens in the nose, sneezing, itching, runny nose, and congestion occur.

Seasonal allergic rhinitis depends on specific plants that are pollenating at that time. In the United States, springtime allergic rhinitis is typically due to pollinating trees. Early summer allergic rhinitis is often due to grass pollination, and allergic rhinitis in the fall is usually due to weeds pollinating. Hypersensitivity to ragweed is very common in autumn. Also in the fall, you may experience allergic symptoms from mold spores on falling leaves.

Perennial allergic rhinitis can be felt year-round and can result from sensitivity to animal proteins, mold, houseplants, and dust mites in carpeting and upholstery. When seeking a medical evaluation for suspected allergic rhinitis, it is important to be aware of the pattern of symptoms (seasonal triggers, indoor vs. outdoor, specific triggers, animal exposure, etc.).

Non-allergic rhinitis and vasomotor rhinitis (a type of non-allergic rhinitis) do not depend on the presence of IgE antibodies, and is not due to an allergic reaction. You can have non-allergic rhinitis even if you test positive for allergies.

Some of the causes of non-allergic rhinitis include:

• Certain infections. In more than 50% of cases, rhinovirus is the responsible agent for common cold (nasopharyngitis), which is the most common clinical form of viral infections.
• Certain medications (various over-the-counter and prescription preparations)
• Eating and drinking (sometimes specific foods, sometimes all food/drink consumption)
• Weather or temperature changes
• Aging
• Hormonal changes or pregnancy
• Consumption of alcohol, especially red wine
• Inflammation or irritation in the nose unrelated to allergy
• Nasal symptoms of other medical conditions

Depending on the type of rhinitis, certain conditions may be associated with rhinitis, such as:

• Asthma
• Acute sinusitis
• Inflammation of the eye (conjunctivitis)
• Atopic dermatitis or eczema
• Poor ventilation of the ears (or eustachian tube dysfunction)
• Laryngitis (inflammation causing hoarseness of voice)
• Eosinophilic esophagitis
• Sleep disturbance

What are the treatment options for rhinitis?

Treating rhinitis depends on the specific cause or diagnosis. If there is a specific trigger that can be avoided, this may be a successful treatment. For example, in people with cat allergy, avoidance of cat exposure and direct contact with cats may help to control symptoms.

Often, medications are used to control symptoms. Depending on the specific cause of the rhinitis symptoms, some of the medications that may be used include:

• Intranasal saline spray or rinse
• Antihistamines (oral or intranasal)
• Corticosteroids (usually applied as an intranasal spray)
• Ipratropium bromide intranasal spray

For allergic rhinitis, allergen immunotherapy may be an option. This is most commonly provided via allergy shots or tablets or liquid drops taken under the tongue. Again, a qualified ENT specialist or allergist should assess your situation to determine whether allergen immunotherapy is an option.

For severe runny nose or nasal obstruction/congestion that does not respond to medications, your ENT specialist may consider additional office procedures or surgery appropriate to your situation.

Allergy

An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are

• Pollen
• Dust mites
• Mold spores
• Pet dander
• Food
• Insect stings
• Medicines
• Latex

Normally, your immune system fights germs. It is your body’s defense system. In most allergic reactions, however, it is responding to a false alarm. Genes and the environment probably both play a role.

Allergies can cause a variety of symptoms such as a runny nose, sneezing, itching, rashes, swelling, or asthma. Allergies can range from minor to severe. Anaphylaxis is a severe reaction that can be life-threatening. Doctors use skin and blood tests to diagnose allergies. Treatments include medicines, allergy shots, and avoiding the substances that cause the reactions.

Hay fever

Hay fever is also known as allergic rhinitis, is an allergic reaction. Each spring, summer, and fall, trees, weeds, and grasses release tiny pollen grains into the air. Some of the pollen ends up in your nose and throat. Hay fever is the most common form of allergy. Symptoms of hay fever are seasonal. You will feel worse when the pollens that affect you are at their highest levels.

If you have allergic rhinitis, your immune system mistakenly identifies a typically harmless substance as an intruder. This substance is called an allergen. The immune system responds to the allergen by releasing histamine and chemical mediators that typically cause symptoms in the nose, throat, eyes, ears, skin and roof of the mouth.

There are 2 forms of allergic rhinitis:

• Seasonal rhinitis (hay fever): Caused by an allergy to pollen and/or mold spores in the air. Pollen is the fine powder that comes from the stamen of flowering plants. It can be carried through the air and is easily inhaled. Symptoms are seasonal and usually occur in spring, late summer, and fall.
• Perennial rhinitis: Caused by other allergens such as dust mites, pet hair or dander, or mold. Symptoms occur year-round.

Seasonal allergic rhinitis (hay fever) is most often caused by pollen carried in the air during different times of the year in different parts of the country.

Allergic rhinitis can also be triggered by common indoor allergens such as the dried skin flakes, urine and saliva found on pet dander, mold, droppings from dust mites and cockroach particles. This is called perennial allergic rhinitis, as symptoms typically occur year-round.

In addition to allergen triggers, symptoms may also occur from irritants such as smoke and strong odors, or to changes in the temperature and humidity of the air. This happens because allergic rhinitis causes inflammation in the nasal lining, which increases sensitivity to inhalants.

Many people with allergic rhinitis are prone to allergic conjunctivitis (eye allergy). In addition, allergic rhinitis can make symptoms of asthma worse for people who suffer from both conditions.

Symptoms of allergic rhinitis

Your symptoms can vary, depending on the severity of your allergies. Symptoms can include:

• Sneezing, often with a runny or clogged nose
• Coughing and postnasal drip
• Itching eyes, nose, throat and skin
• Runny nose.
• Stuffy nose.
• Headache.
• Pressure in the nose and cheeks.
• Ear fullness and popping.
• Sore throat.
• Watery, red, or swollen eyes.
• Dark circles under your eyes.
• Trouble smelling.
• Hives.

Allergic rhinitis can last several weeks, longer than a cold or the flu. It does not cause fever. The nasal discharge from hay fever is thin, watery, and clear. Nasal discharge from a cold or the flu tends to be thicker. Itching (mostly in the eyes, nose, mouth, throat, and skin) is common with hay fever but not with a cold or the flu. Sneezing is more prominent with hay fever. You may even have severe sneeze attacks.

What causes allergic rhinitis?

You have an allergy when your body overreacts to things that don’t cause problems for most people. These things are called allergens. If you have allergies, your body releases chemicals when you are exposed to an allergen. One type of chemical that your body releases is called histamine. Histamine is your body’s defense against the allergen. The release of histamine causes your symptoms.

Hay fever is an allergic reaction to pollen. Pollen comes from flowering trees, grass, and weeds. If you are allergic to pollen, you will notice your symptoms are worse on hot, dry days when wind carries the pollen. On rainy days, pollen often is washed to the ground, which means you are less likely to breathe it.

• Allergies that occur in the spring (late April and May) are often due to tree pollen.
• Allergies that occur in the summer (late May to mid-July) are often due to grass and weed pollen.
• Allergies that occur in the fall (late August to the first frost) are often due to ragweed.

Allergens that can cause perennial allergic rhinitis include:

• Mold. Mold is common where water tends to collect, such as shower curtains and damp basements. It can also be found in rotting logs, hay, and mulch. This allergy is usually worse during humid and rainy weather.
• Animal dander. Proteins found in the skin, saliva, and urine of furry pets such as cats and dogs are allergens. You can be exposed to dander when handling an animal or from house dust that contains dander.
• Dust. Many allergens, including dust mites, are in dust. Dust mites are tiny living creatures found in bedding, mattresses, carpeting, and upholstered furniture. They live on dead skin cells and other things found in house dust.

How is allergic rhinitis diagnosed?

If your symptoms interfere with your daily life, see your family doctor. Your doctor will ask you questions about your symptoms and medical history and perform a physical exam. Keeping a record of your symptoms over a period of time can help your doctor determine what triggers your allergies.

Your doctor may want to do an allergy skin test to help determine exactly what you are allergic to. During an allergy skin test, tiny amounts of allergens are applied to your skin. Your doctor will observe and record the way your skin reacts to each allergen.

Your doctor may also decide to do a blood test, such as the radioallergosorbent test (RAST). This test identifies antibodies in your blood that determine what you’re allergic to. Once your allergens are identified, you and your doctor can decide the best treatment.

Can allergic rhinitis be prevented or avoided?

Allergic rhinitis cannot be prevented. You can help your symptoms by avoiding the things that you are allergic, including:

• Keeping windows closed. This is especially important during high-pollen seasons.
• Washing your hands after petting animals.
• Using dust- and mite-proof bedding and mattress covers.
• Wearing glasses outside to protect your eyes.
• Showering before bed to wash off allergens from hair and skin.

You can also AVOID things that can make your symptoms worse, such as:

• aerosol sprays
• air pollution
• cold temperatures
• humidity
• irritating fumes
• tobacco smoke
• wind
• wood smoke.

Allergic rhinitis treatment

Several medicines can be used to treat allergies. Your doctor will help you determine what medicine is best for you depending on your symptoms, age, and overall health. These medicines help prevent symptoms if you use them regularly, before you’re exposed to allergens.

• Antihistamines help reduce the sneezing, runny nose, and itchiness of allergies. These come in pill form and as nasal sprays. Many are available over the counter. Some require a prescription.
• Decongestants, such as pseudoephedrine and phenylephrine, help temporarily relieve the stuffy nose of allergies. Decongestants are found in many medicines and come as pills, nose sprays, and nose drops. They are best used only for a short time. Nose sprays and drops shouldn’t be used for more than 3 days because you can become dependent on them. This causes you to feel even more stopped-up when you try to quit using them. You can buy decongestants without a doctor’s prescription. However, decongestants can raise your blood pressure. Talk your family doctor before using them if you have high blood pressure.
• Cromolyn sodium is a nasal spray that helps prevent the body’s reaction to allergens. This medicine may take 2 to 4 weeks to start working. It is available without a prescription.
• Nasal steroid sprays reduce the reaction of the nasal tissues to inhaled allergens. This helps relieve the swelling in your nose so that you feel less stopped-up. They are the most effective at treating patients who have chronic symptoms. Many nasal steroids are now available without a prescription. You won’t notice their benefits for up to 2 weeks after starting them.
• Eye drops. If your other medicines are not helping enough with your itchy, watery eyes, your doctor may prescribe eye drops for you. Some are available over the counter.
• Allergy shots or sublingual tablets (also called immunotherapy) are an option for people who try other treatments but still have allergy symptoms. These shots or dissolvable tablets contain a very small amount of the allergen you are allergic to. They’re given on a regular schedule so that your body gets used to the allergens. This helps decrease your body’s sensitivity to the allergens. Over time, your allergy symptoms will become less severe.

Living with allergic rhinitis

Living with the symptoms of allergic rhinitis can affect your daily life. Nasal symptoms can be worse when lying down. This can disturb your ability to sleep well. Fatigue and headaches can affect your ability to function at school and work. There are many medicines and treatments that can help you manage your symptoms. Talk to your doctor as soon as you feel that your symptoms are getting worse or are not easy to control. He or she can help you come up with the right plan to control them so they don’t affect your ability to live your normal life.

Photic sneeze reflex

It seems that some people really do sneeze when they look at the sun, or actually at any bright light (there is nothing special about the sun). The photic sneeze reflex is also called ACHOO (autosomal dominant compelling helio-ophthalmic outburst) syndrome ⁵. This reflex was first described in the medical literature by Sedan ⁶. It was shown to have an autosomal dominant inheritance pattern and is assumed to affect 1735% of the world population ⁷. The photic sneeze reflex has been reported to be present in 23% of medical students ⁸. In a study of 460 blood donors, photic sneezing was found in 24% ⁹.

Scientists do not know exactly why this happens, but it might reflect a ‘crossing’ of pathways in the brain, between the pupillary light reflex arc and the sneezing reflex arc. The reflex can be triggered only after the first exposure to light, never on repetitive stimulation and many reports cite a refractory period before the reflex can be elicited suggesting that a polysynaptic pathway is involved. The first theory concerning the pathways mentioned belongs to Eckhardt et al. ¹⁰ who suggested that stimulation of the optic nerve triggers the trigeminal nerve. The afferent impulses of the pupillary light reflex are transmitted via the optic nerve while the efferent impulses are transmitted via the oculomotor nerve. According to this theory, an indirect impulse is transmitted to the ophthalmic division of the trigeminal nerve. This impulse generates the nasal stimulation that causes sneezing by affecting the maxillary division of the trigeminal nerve as well. The second theory of crossing pathways belongs to Watson. Light falling on the retina stimulates afferent fibers to the pretectal nuclei, which then send interneurons to the Edinger-Westphal nuclei. The parasympathetic fibers from the Edinger-Westphal nuclei and the trigeminal afferent fibers from the cornea both pass through the ciliary ganglion, where they may participate in transmission ¹¹. Parasympathetic generalization may also contribute to photic sneeze. Stimuli which excite primarily one branch of the parasympathetic nervous system tend to activate other branches. Thus, the parasympathetic branches of the oculomotor nerve which are activated to generate pupillary constriction against the bright light cause secretion and congestion in the nasal mucosa by triggering the parasympathetic activation by the pterygopalatine ganglion. This process triggers  sneezing ¹².

Physical stimulants of the trigeminal nerve

Physical or mechanical stimulants in the innervation zone of the trigeminal nerve may trigger the sneezing reflex. Some of these stimulants include pulling hair, tearing off eyebrows or orbital injections administered frequently during ocular surgery under local anesthesia ¹³.

Central nervous system pathologies

Lateral medullary syndrome or Wallenberg’s syndrome, often results from occlusion or dissection of the vertebral artery. Vertebral artery dissection has been blamed on many different life events, such as sneezing ¹⁴. Paroxysmal sneezing at the onset of lateral medullary syndrome is usually interpreted as a cause, since a violent sneeze could potentially result in a vertebral artery dissection. Due to inactivation of the sneezing center in lateral medullary syndrome, sneezing cannot occur although the sensation of sneezing is present ¹⁵. Localization of the human sneeze center was described in a patient with right lateral medullary syndrome, initially presenting with violent sneezes and followed by a brief loss of the sneeze reflex with eventual recovery ¹⁶.

Sneezing may commonly accompany temporal lobe and grand-mal epilepsy. It may be observed during the aura prior to an epileptic seizure or it may develop as an autonomic reflexive response during the seizure as well ¹⁷. Beverwyck ¹⁸ commented upon the analogy of the epileptic seizure with hiccups and sneezing and noted that the physiological and anatomical basis for such a hypothesis remained to be unexplained. In the mid-nineteenth century Jackson used the term epilepsy ‘as the name for occasional, sudden, excessive, rapid and local discharges of grey matter’ ¹⁹. Jackson ¹⁹ further commented upon the healthy and yet random discharge and concluded that ‘a sneeze is a sort of healthy epilepsy’.

Psychogenic (intractable) sneezing

Intractable sneezing, first described by Shilkrel in 1949, is a rare pathological condition that has been detected in more than 50 cases in literature to date ²⁰. Kanner ²¹ referred to a 13-year-old girl who had incessant sneezing for over 2 months and whose progress was followed by a daily newspaper communique. A diagnosis of hysteria was made and subsequent psychotherapy eliminated the sneezing. Yater ²² referred to similar explosive repetitious episodes and considered them to be a sort of imitation of the true act of sneezing.

Psychogenic intractable sneezing occurs mainly in adolescent girls for which a cause may not be found. Patients are usually refractory to various medications and have an otherwise unremarkable extensive workup ²³. Inspiratory phase is quite short and the amount of nasal mucosal secretion expelled very low. Eyes may remain open during sneezing. It usually develops due to psychogenic factors and is refractory to medical treatment ²⁴. Psychogenic sneezing responds well to psychological measures such as psychotherapy, biofeedback, relaxation exercises, supportive psychotherapy (i.e. explanation of nature of illness, suggestion to overcome symptoms) and behavior therapy (reward when there is symptom reduction, aversion therapy, hypnosis and relaxation). The role of anxiolytic drugs lies in reducing underlying anxiety and making the patient more amenable to psychotherapy.

Snatiation reflex

An uncontrollable sneezing attack developing as a result of stretching of the stomach following an excessive nutrition are first described by Teebi and Al-Saleh ²⁵ as a reflex with an autosomal dominant inheritance pattern. The mechanism of development is unknown. Snatiation is a combination of the words ‘sneeze’ and ‘satiation’. Snatiation also stands for ‘Sneezing Noncontrollably At a Tune of Indulgence of the Appetite-a Trait Inherited and Ordained to be Named’ ²⁶. This abbreviation was supposed to facilitate future cases to be evaluated in the same class. Recently, two patients have been reported, who state that several members of their family sneeze on a full stomach ²⁷. This report doubles the number of families with the snatiation reflex in the medical literature.

Sexual ideation or orgasm

An association between sexual excitement and sneezing was first described in the nineteenth century followed by a young German otolaryngologist who developed a theory of ‘nasal reflex neurosis’ due to the finding of erectile tissue in both nasal mucous membranes and genital areas ²⁸. The first report of this phenomenon in the literature describes a 69-year-old man who complained of severe sneezing immediately following orgasm, with no associated psychiatric morbidity ²⁹, described male orgasm as a precipitant for the sneeze reflex. Recently, Bhutta ³⁰ described a middle-aged man with uncontrollable fits of sneezing with sexual thought. The patient had no other rhinological symptoms and psychiatric morbidity. Bhutta et al. ²⁷ performed a search of Internet ‘chatrooms’ and found 17 people of both sexes reporting sneezing immediately upon sexual ideation, and three people after orgasm. Although Internet reports do not give an accurate incidence, their findings do suggest that it is much more common than is currently recognized.

Sneezing pathophysiology

The sneezing reflex may be divided into two phases. The first is a nasal or sensitive phase, following stimulation of the nasal mucosa by chemical or physical irritants. Many distal branches of trigeminal nerve terminate in the facial skin transmitting tactile, pain and temperature sensations, while some branches distribute in the nasal mucosal epithelium ³¹. These branches are myelinated sensory fibers of small diameter, which terminate with receptor endings. Some of these receptors are triggered by chemical stimuli while others are sensitive to tactile and mechanical stimuli ³¹. Afferent neural stimuli are transmitted to the trigeminal ganglion via anterior ethmoidal, posterior nasal, infraorbital and ophthalmic branches of the trigeminal nerve ³². Through the trigeminal ganglion the stimuli reach the sneezing center in the lateral medulla ³³. Upon reaching a threshold, the second phase the efferent or respiratory phase begins once a critical number of inspiratory and expiratory neuron has been recruited ³⁴. This consists of eye closing, deep inspiration, and then a forced expiration with initial closing of the glottis, and increasing intrapulmonary pressure. The sudden dilatation of the glottis gives rise to an explosive exit of air through the mouth and nose, washing out mucosal debris and irritants.

The trigeminal nerve is important for the nociceptive sensory supply of the nasal mucosa in addition to the face, oral mucosa, cornea and conjunctiva. Itching and sneezing are generated by the activation of trigeminal afferent nerve terminals in the nasal mucosa ³⁵. These nociceptive nerve fibers consist mainly of two types of fiber: The thin Ad-fibers that mediate acute perceptions with a quick adaptation and activation only during the actual irritation and the nonmyelinated C-fibers which adapt slowly and communicate dull burning, difficult to locate perceptions, which outlast acute pain ³⁶. In allergic rhinitis, immunologically triggered inflammation results in the recruitment and activation of both types of fiber that results in itching and sneezing ³⁷. The number of particles expelled during a forceful sneeze, of which the sizes range from 0.5 to 5 mm, is estimated to be 40,000. The estimations concerning the speed of a sneeze range between 150 km/h and 1045 km/h (nearly 85% of the velocity of sound) ³⁸.

How to stop sneezing

Avoiding exposure to the allergen is the best way to control sneezing caused by allergies. An allergen is something that causes an allergic reaction.

Tips to reduce your exposure to allergens:

• Change furnace filters
• Remove pets from the home to get rid of animal dander
• Use air filters to reduce pollen in the air
• Wash linens in hot water (at least 130°F or 54°C) to kill dust mites

In some cases, you may need to move out of a home with a mold spore problem.

Sneezing that is not due to an allergy will disappear when the illness that is causing it is cured or treated.

When to contact a medical professional

Call your health care provider if sneezing is affecting your life and home remedies do not work.

What to expect at your doctor visit

Your doctor will perform a physical exam and look at your nose and throat. You’ll be asked about your medical history and symptoms. Questions may include when the sneezing started, whether you have other symptoms, or if you have allergies.

In some cases, allergy testing may be needed to find the cause.

Your doctor will suggest treatments and lifestyle changes for hay fever symptoms.

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