Allergen immunotherapy is useful for environmental allergies, allergies to insect bites, and asthma. Its benefit for food allergies is unclear and thus not recommended. Immunotherapy involves exposing people to larger and larger amounts of allergen in an effort to change the immune system's response.

Meta-analyses have found that injections of allergens under the skin is effective in the treatment in allergic rhinitis in children and in asthma. The benefits may last for years after treatment is stopped. It is generally safe and effective for allergic rhinitis and conjunctivitis, allergic forms of asthma, and stinging insects.

The evidence also supports the use of sublingual immunotherapy for rhinitis and asthma but it is less strong. For seasonal allergies the benefit is small. In this form the allergen is given under the tongue and people often prefer it to injections. Immunotherapy is not recommended as a stand-alone treatment for asthma.

Several medications may be used to block the action of allergic mediators, or to prevent activation of cells and degranulation processes. These include antihistamines, glucocorticoids, epinephrine (adrenaline), mast cell stabilizers, and antileukotriene agents are common treatments of allergic diseases. Anti-cholinergics, decongestants, and other compounds thought to impair eosinophil chemotaxis, are also commonly used. Though rare, the severity of anaphylaxis often requires epinephrine injection, and where medical care is unavailable, a device known as an epinephrine autoinjector may be used.

Antihistamines can alleviate some of the milder symptoms of an allergic reaction, but do not treat all symptoms of anaphylaxis. Antihistamines block the action of histamine, which causes blood vessels to dilate and become leaky to plasma proteins. Histamine also causes itchiness by acting on sensory nerve terminals. The most common antihistamine given for food allergies is diphenhydramine.

Epinephrine is another name for the hormone adrenaline, which is produced naturally in the body. An epinephrine injection is the first-line treatment for severe allergic reactions (anaphylaxis). If administered in a timely manner, epinephrine can reverse its effects.

Epinephrine relieves airway swelling and obstruction, and improves blood circulation; blood vessels are tightened and heart rate is increased, improving circulation to body organs. Epinephrine is available by prescription in an autoinjector.

Cat allergies can often be controlled with over the counter or prescription medications. Antihistamines and decongestants may provide allergy relief.

Treatment for accidental ingestion of milk products by allergic individuals varies depending on the sensitivity of the person. An antihistamine such as diphenhydramine (Benadryl) may be prescribed. Sometimes prednisone will be prescribed to prevent a possible late phase Type I hypersensitivity reaction. Severe allergic reactions (anaphalaxis) may require treatment with an epinephrine pen, i.e., an injection device designed to be used by a non-healthcare professional when emergency treatment is warranted. A second dose is needed in 16-35% of episodes.

Antihistamines such as diphenhydramine and chlorpheniramine are commonly used as treatment. People treated with H1 antihistamines exhibit reduced production of histamine and leukotrienes as well as downregulation of adhesion molecule expression on the vasculature which in turn attenuates allergic symptoms by 40–50%.

Dual-action medications are also prescribed frequently. Olopatadine (Patanol) and ketotifen fumarate (Alaway or Zaditor) both provide protection by acting as an antihistamine and a mast cell stabilizer together. Patanol is a prescription medication, whereas ketotifen fumarate is not.

A systematic review of 30 trials, with 17 different treatment comparisons found that all topical antihistamines and mast cell stabilizers included for comparison were effective in reducing symptoms of seasonal allergic conjunctivitis. There was not enough evidence to determine differences in long-term efficacy among the treatments.

Many of the eye drops can cause burning and stinging, and have side-effects. Proper eye hygiene can improve symptoms, especially with contact lenses. Avoiding precipitants, such as pollen or mold can be preventative.

Mast cell stabilizers can help people with allergic conjunctivitis. They tend to have delayed results, but they have fewer side-effects than the other treatments and last much longer than those of antihistamines. Some people are given an antihistamine at the same time so that there is some relief of symptoms before the mast cell stabilizers becomes effective. Doctors commonly prescribe lodoxamide and nedocromil as mast cell stabilizers, which come as eye drops.

A mast cell stabilizer is a class of non-steroid controller medicine that reduces the release of inflammation-causing chemicals from mast cells. They block a calcium channel essential for mast cell degranulation, stabilizing the cell, thus preventing the release of histamine. Decongestants may also be prescribed. Another common mast cell stabilizer that is used for treating allergic conjunctivitis is sodium cromoglicate.

There is active research on trying oral immunotherapy (OIT) to desensitize people to egg allergens. A Cochrane Review concluded that OIT can desensitize people, but it remains unclear whether long-term tolerance develops after treatment ceases, and 69% of the people enrolled in the trials had adverse effects. They concluded there was a need for standardized protocols and guidelines prior to incorporating OIT into clinical practice. A second review noted that allergic reactions, up to anaphylaxis, can occur during OIT, and recommends this treatment not be routine medical practice. A third review limited its scope to trials of baked egg-containing goods such as bread or cake as a means of resolving egg allergy. Again, there were some successes, but also some severe allergic reactions, and the authors came down on the side of not recommending this as treatment.

Currently there is no cure for allergic reactions to peanuts other than strict avoidance of peanuts and peanut-containing foods. Extra care needed for food consumed at or purchased from restaurants. The principal treatment for anaphylaxis is epinephrine as an injection.

Some allergy sufferers find relief in allergen immunotherapy, a periodic injection therapy designed to stimulate the body's natural immune responses to the cat allergens.

Treatment for accidental ingestion of soy products by allergic individuals varies depending on the sensitivity of the person. An antihistamine such as diphenhydramine (Benadryl) may be prescribed. Sometimes prednisone will be prescribed to prevent a possible late phase Type I hypersensitivity reaction. Severe allergic reactions (anaphalaxis) may require treatment with an epinephrine pen, i.e., an injection device designed to be used by a non-healthcare professional when emergency treatment is warranted. A second dose is needed in 16-35% of episodes.

The need for a dairy-free diet should be reevaluated every six months by testing milk-containing products low on the "milk ladder", such as fully cooked, i.e., baked foods containing milk, in which the milk proteins have been denatured, and ending with fresh cheese and milk. Desensitization via oral immunotherapy holds some promise but is still being actively researched (see Research).

Treatment for accidental ingestion of milk products by allergic individuals varies depending on the sensitivity of the person. An antihistamine such as diphenhydramine (Benadryl) may be prescribed. Sometimes prednisone will be prescribed to prevent a possible late phase Type I hypersensitivity reaction. Severe allergic reactions (anaphalaxis) may require treatment with an epinephrine pen, i.e., an injection device designed to be used by a non-healthcare professional when emergency treatment is warranted. A second dose is needed in 16-35% of episodes.

Allergen immunotherapy (AIT, also termed desensitization) treatment involves administering doses of allergens to accustom the body to substances that are generally harmless (pollen, house dust mites), thereby inducing specific long-term tolerance. Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous).

Intranasal corticosteroids are used to control symptoms associated with sneezing, rhinorrhea, itching, and nasal congestion. Steroid nasal sprays are effective and safe, and may be effective without oral antihistamines. They take several days to act and so must be taken continually for several weeks, as their therapeutic effect builds up with time.

In 2013, a study compared the efficacy of mometasone furoate nasal spray to betamethasone oral tablets for the treatment of people with seasonal allergic rhinitis and found that the two have virtually equivalent effects on nasal symptoms in people.

Systemic steroids such as prednisone tablets and intramuscular triamcinolone acetonide or glucocorticoid (such as betamethasone) injection are effective at reducing nasal inflammation, but their use is limited by their short duration of effect and the side-effects of prolonged steroid therapy.

Immunotherapy involves attempts to reduce or eliminate allergic sensitivity by repeated exposure. This active research concept involves swallowing small amounts of peanuts, holding a peanut product under the tongue - sublingual immunotherapy - skin patches or injections. None of these are considered ready for use in people outside of carefully conducted trials. In those with mild peanut allergies, gradually eating more and more peanuts resulted in at least some short-term benefits. Due to the amount of evidence being small and the high rate of adverse effects, this is not currently recommended as treatment. Sublingual immunotherapy involves putting gradually increasing doses of an allergy extract under a person's tongue. The extract is then either spat or swallowed. It is not currently recommended as treatment; however, it is being studied. Epicutaneous immunotherapy involves giving the allergen through a patch. Trials are ongoing.

Some symptoms might weaken if people get allergy shots. After getting several treatments for a long time, some allergic people will not have reactions afterwards.

Some reactions have been eased by replacing original rice with genetically modified rice. This is regarded as a new choice for rice allergic people.

Reactions might lessen by staying away from rice long-term.

OAS must be managed in conjunction with the patient's other allergies, primarily the allergy to pollen. The symptom severity may wax and wane with the pollen levels. Published pollen counts and seasonal charts are useful but may be ineffective in cases of high wind or unusual weather, as pollen can travel hundreds of kilometers from other areas.

In addition, patients are advised to avoid the triggering foods, particularly nuts.

Peeling or cooking the foods has been shown to eliminate the effects of some allergens such as "mal d 1" (apple), but not others such as celery or strawberry. In the case of foods such as hazelnut, which have more than one allergen, cooking may eliminate one allergen but not the other.

Antihistamines may also relieve the symptoms of the allergy by blocking the immune pathway. Persons with a history of severe anaphylactic reaction may carry an injectable emergency dose of epinephrine (such as an EpiPen). Oral steroids may also be helpful. Allergy immunotherapy has been reported to improve or cure OAS in some patients. Immunotherapy with extracts containing birch pollen may benefit OAS sufferers of apple or hazelnut related to birch pollen-allergens. Even so, the increase in the amount of apple/hazelnut tolerated was small (from 12.6 to 32.6 g apple), and as a result, a patient's management of OAS would be limited.

Once a nickel allergy is detected, the best treatment is avoidance of nickel-releasing items. It is important to know the main items that can cause nickel allergy, which may be remembered using the mnemonic "BE NICKEL AWARE". The top 13 categories that contain nickel include beauty accessories, eyeglasses, money, cigarettes, clothes, kitchen and household, electronics and office equipment, metal utensils, aliment, jewelry, batteries, orthodontic and dental appliances, and medical equipment. Other than strict avoidance of items that release free nickel, there are other treatment options for reduction of exposure. The first step is to limit friction between skin and metallic items. Susceptible people may try to limit sweating while wearing nickel items, to reduce nickel release and thus decrease chances for developing sensitization and/or allergy. Another option is to shield electronics, metal devices, and tools with fabric, plastic, or acrylic coverings. Dermatological application tests has shown that barrier creams effectively prevent the symptoms of nickel allergy, such as the Nidiesque™.

There are test kits that can be very helpful to check for nickel release from items prior to purchasing. The ACDS providers can give a guidance list of safe items. In addition to avoidance, healthcare providers may prescribe additional creams or medications to help relieve the skin reaction.

Most people find it necessary to strictly avoid any item containing dairy ingredients. Milk from other species (goat, sheep...) should not be substituted for cow's milk, as milk proteins from other mammals are often cross-reactive. Beyond the obvious (anything with milk, cheese, cream, butter or yogurt in the name), food ingredient lists need to be examined:

- Ghee

- Some Margarine (!)

- Medical food beverages (Ensure, etc.)

- "Non-dairy" coffee creamer

- Eggnog

- Sherbet

- "Cream of..." soups

- Creamy pasta sauces

- Creamy salad dressings

- Nutella

- Simplesse

- Bread

- Baked goods

- Crackers

- Cereals

- Some Chewing gum (!)

- Some Hot dogs (!)

- Instant mashed potatoes

- Flavored potato chips

- Caramel and nougat candy

- casein (milk protein

- whey (milk protein)

- Lactalbumin (milk protein)

- lactoglobulin (milk protein)

- lactoferrin (milk protein)

Probiotic products have been tested, and some found to contain milk proteins which were not always indicated on the labels.

Completely eliminating salicylate from one's diet and environment is virtually impossible and is not a recommended course of action by many immunologists. The range of foods that have no salicylate content is very limited, and consequently salicylate-free diets are very restricted.

Desensitization involves daily administration of progressive doses of salicylate. This process is usually performed as an inpatient, with a crash-cart at the bedside over a six-day period, beginning with 25 mg of I.V. lysine-aspirin and progressing to 500 mg if tolerated.

Montelukast is one form of treatment used in aspirin-intolerant asthma.

Avoiding allergens will help prevent symptoms. Allergies that a child has to the family pet can be controlled by removing the animal and finding it a new home. Exterminating cockroaches, mice and rats and a thorough cleaning can reduce symptoms of an allergy in children. Dust mites are attracted to moisture. They consume human skin that has come off and lodged in, furniture, rugs, mattresses, box springs, and pillows. The child's bedding can be covered with allergen-proof covers. Laundering of the child's clothing, bed linens and blankets will also reduce exposure.

Exposure to allergens outside the home can be controlled with the use of air conditioners. Washing the hair, taking a bath or shower before bedtime can be done to remove allergens that have been picked up from outside the home. If grass or grass pollen is an allergen it is sometimes beneficial to remain indoors while grass is being cut or mowed. Children with allergies to grass can avoid playing in the grass to prevent allergic symptoms. Staying out of piled leaves in the fall can help. Pets returning into the home after being outdoors may track in allergens.

For those allergic to fruits, cooking may help reduce or eliminate the reaction to some fruits.

People with this allergy might not necessarily be allergic to citrus fruits.

The clinical expression of the dermatitis can be mitigated by avoidance of the allergen. Through compliance with avoidance measures, the immune system can become less stimulated. The key to avoidance is proper evaluation and detection of the inciting allergen. However, once the immune system registers the allergen, the recognition is permanent.

The first step in treating the condition is appropriate recognition of the clinical problem, followed by identification of the culprit chemical and the source of that chemical. Corticosteroid creams should be used carefully and according to the prescribed directions because when overused over longer periods of time they can cause thinning of the skin. Also, in some instances such as poison ivy dermatitis calamine lotion and cool oatmeal baths may relieve itching.

Usually, severe cases are treated with systemic corticosteroids which may be tapered gradually, with various dosing schedules ranging from a total of 12 – 20 days to prevent the recurrence of the rash (while the chemical allergen is still in the skin, up to 3 weeks, as well as a topical corticosteroid. Tacrolimus ointment or pimecrolimus cream can also be used additionally to the corticosteroid creams or instead of these. Oral antihistamines such as diphenhydramine or hydroxyzine may also be used in more severe cases to relieve the intense itching. Topical antihistamines are not advised as there might be a second skin reaction (treatment associated contact dermatitis) from the lotion itself.

The other symptoms caused by allergic contact dermatitis may be eased with cool compresses to stop the itching. It is vital for treatment success that the trigger be identified and avoided. The discomfort caused by the symptoms may be relieved by wearing smooth-textured cotton clothing to avoid frictional skin irritation or by avoiding soaps with perfumes and dyes.

Commonly, the symptoms may resolve without treatment in 2 to 4 weeks but specific medication may hasten the healing as long as the trigger is avoided. Also, the condition might become chronic if the allergen is not detected and avoided.

The preferred treatment for many patients is desensitization to aspirin, undertaken at a clinic or hospital specializing in such treatment. In the United States, the Scripps Clinic in San Diego, CA, the Massachusetts General Hospital in Boston, MA, the Brigham and Women's Hospital in Boston, MA, National Jewish Hospital in Denver and Stanford University Adult ENT Clinic have allergists who routinely perform aspirin desensitization procedures for patients with aspirin-induced asthma. Patients who are desensitized then take a maintenance dose of aspirin daily and while on daily aspirin they often have reduced need for supporting medications, fewer asthma and sinusitis symptoms than previously, and many have an improved sense of smell. Desensitization to aspirin reduces the chance of nasal polyp recurrence, and can slow the regrowth of nasal polyps. Even patients desensitized to aspirin may continue to need other medications including nasal steroids, inhaled steroids, and leukotriene antagonists.

Leukotriene antagonists and inhibitors (montelukast, zafirlukast, and zileuton) are often helpful in treating the symptoms of aspirin-induced asthma. Some patients require oral steroids to alleviate asthma and congestion, and most patients will have recurring or chronic sinusitis due to the nasal inflammation.