Medications for Allergy

Diagnosing and treating allergies

When a physician is evaluating a person for allergies, there are several steps involved. First, the patient’s history is taken. Then, the patient is examined. Depending on the patient’s symptoms, several tests might be done. Since some medications (especially antihistamines) can affect test results, a person should ask the health care provider which medications should be stopped days before the testing is to take place.

Skin (scratch or puncture) testing

In this test, a variety of substances that are common to the region in which the person lives are evaluated. Tiny amounts of fluids containing allergens such as pollen, animal dander, dust mites, and molds are placed just under the surface of the skin. Within 15-20 minutes, swelling occurs at the site of any substance to which the person has an allergy. The severity of the reaction can indicate the person’s level of sensitivity.

Virtually painless, this form of testing offers immediate results and almost no risk of serious allergic reaction. This test is usually used to assess reactions to respiratory allergens.

Intradermal testing

These tests are similar to scratch or puncture tests, but are slightly more involved. Tiny amounts of allergens are injected under the skin. Intradermal tests are often done if the scratch or puncture test results are not complete or useful.

Blood (RAST) testing

In these tests, a person’s blood is combined with an allergen to determine whether any IgE antibodies react. If there is a reaction, there is likely an allergy to the tested substance. Although slightly more expensive than skin tests, this test is relatively painless, offers fast results, and provides almost no risk of serious allergic reaction. Blood testing is often used to evaluate reactions to insects and medications in people for whom skin testing is not an option.

Patch testing

For this type of test, allergen-specific adhesive patches are placed on a person’s skin and left for 72 hours. The sites that show swelling or redness indicate an allergic response. This form of testing is commonly used to assess reactions to metals and cosmetic additives.

Provocative testing

This type of testing is also called challenge testing. Usually, the substance in question is administered in an effort to provoke symptoms gradually. A trace amount of the allergen might be administered in an aerosol spray. The person’s reaction to the allergen indicates to the physician both the nature of and the severity of the symptoms. Provocative testing can be uncomfortable. Severe allergic reactions can occur.

An infant’s sensitivity to a food or even a food allergy might be diagnosed at home first. If a parent knows that there is a family history of food allergies, there is a way to avoid having an infant experience full-blown symptoms. By gradually introducing small amounts of new foods — one at a time — parents can isolate a reaction. If a few foods are grouped together in a single meal, it is far more difficult to figure out which one is causing the reaction. If, however, a parent already suspects that a child has a food allergy, it is best not to test this suspicion any further at home. Safer testing can be done in an allergist’s office.

A person can be treated for allergies, but not cured. The range of treatment options provides some relief for most people. As mentioned earlier, one common form of treatment involves ongoing allergen immunotherapy (also called allergy desensitization injections). Those who suffer from reactions to airborne allergens and insect stings find this form of treatment quite beneficial. Over time, a series of injections containing the offending allergens is given in an effort to build the immune system‘s defenses against them.

When a person first begins allergen immunotherapy, a very diluted form of the allergen compound is given. Gradually, more of the substance is added to the injection. Eventually, the allergist determines that the optimal dose has been reached. The allergist could also determine that the person is at risk of developing an allergic reaction if the injections continue. Whatever the determination is, at this point the therapy ends.

The entire process of allergen immunotherapy can last for years. There is some evidence that this type of therapy works by tricking the immune system. As increased amounts of the allergen are injected, the immune system starts to produce a blocking antibody (IgG). The IgG antibody competes with the allergy antibodies (IgE) for the allergen, takes it over, and then does two things that halt an allergic reaction: It prevents the mast cells from activating and it stops the release of histamines.

Most of the oral medications that are used to treat allergies fall into two categories: antihistamines and decongestants. Antihistamines prevent a histamine — a chemical that the body produces during an allergic reaction — from taking effect. Antihistamines are available over-the-counter in tablet and liquid form; they are also available as tablets, liquids, and injections with a prescription. Decongestants work by shrinking blood vessels and decreasing fluid leakage so that nasal congestion is reduced. Both liquid and tablet forms are available as over-the-counter and prescribed medications. Often, antihistamines and decongestants are combined in a single medication to address a greater number of symptoms.

For an acute allergic reaction that involves a great deal of congestion, a physician might recommend a decongestant in the form of drops or a nose spray. The over-the-counter form of medication should not be used for more than three or four consecutive days. Otherwise, it can actually increase nasal congestion. A prescription form of this medication can be used for a longer period without producing this side effect.

Nasal steroid inhalers or sprays can offer fast relief by reducing inflammation and swelling, as well as by slowing the rate at which histamines are released. These sprays deliver a very fine mist directly into the lining of the nose. They temporarily constrict the blood vessels in the swollen tissues within the nose. They also temporarily open a larger passage to allow for the free flow of air. When the effects of the spray wear off, the swelling returns. Sometimes, the swelling has grown worse. When this happens, most people just reuse the spray. Unfortunately, a series of brief periods of relief can lead to longer bouts of congestion. It is important to note that decongestant nasal sprays can be overused. If a person does overuse these sprays, his or her heart rate can increase and blood pressure can rise.

The good news is that most allergy symptoms can be treated easily and safely. The bad news is that, on rare occasions, an allergic reaction can be deadly. As we discussed earlier, anaphylaxis is a severe, sometimes fatal, allergic reaction. It is usually treated with an injection of epinephrine, and antihistamines and steroids are also given. The sooner the allergic person gets treatment, the less severe the symptoms will be. Epinephrine can stop the progression of anaphylaxis; antihistamines and steroids cannot. Antihistamines and steroids should never be given instead of epinephrine, because, while they can help recovery, they cannot reverse the symptoms of anaphylaxis.

Often, a person who has a severe food allergy learns about it only after exposure to the trigger. Such exposure can happen as a result of breathing in or eating the substance. After the symptoms are treated, contact an allergist for follow-up care. The allergist can help determine what trigger caused the reaction. This is very important in preventing anaphylaxis from happening again.

Although triggers that are foods may be easy to avoid, it might be trickier when the allergen is a food additive. This is why it is crucial to be under a doctor’s care. If anaphylaxis happens again, the person might already have an injection of epinephrine handy. Using this medicine will keep symptoms under control until the person can be taken to a hospital. An allergist can even offer treatments that can help build immunity to some triggers. For example, if anaphylaxis is triggered by insect stings, ongoing allergy shots can help build tolerance to the venom.

Here are some suggestions for what can be done to assist someone who is experiencing anaphylaxis:

1. Ahead of time, learn enough about the symptoms to recognize when the reaction is occurring.

2. Get medical help as soon as possible.

3. Do not allow a person who is undergoing this type of reaction to drive.

4. Even if the person receives treatment at the location where the reaction occurred, it is vital that he or she go to an emergency room, where the condition can be monitored.

5. Make a note of what could have caused the reaction and what amount of time elapsed between exposure and reaction. Having this information could help to prevent a future reaction.

Preventing and controlling allergies

For most allergies, preventing or controlling symptoms requires a few simple steps. Depending on the severity and frequency of the reaction, almost all symptoms can be minimized by changes in environment and the person’s behavior. Once the triggers are known, they should be avoided. Changes to the home, school, and work environments can significantly reduce the person’s exposure to a variety of allergens.

The most important behavioral change that a person can make to help prevent and control allergies is to use all available methods of treatment. Allergen immunotherapy can help build tolerance against specific allergens. Other medications can help prevent or control symptoms that do recur. A person who suffers from allergies can also improve his or her general health by eating nutritious foods, exercising regularly, and getting enough rest.

At the very beginning of life and during early childhood, measures can be taken to help prevent some allergies. Researchers have known for some time that breast milk is far more nutritious for infants than formula, cow’s milk, or soy milk. Studies show that infants who are breast-fed are less likely to develop allergies to a variety of substances. The lower incidence of allergy in children who were breastfed might result from the mother’s immunities being transferred to the child through the breast milk.

Asthma and Allergies: The Science Inside

Another way to help lower the risk of allergy — specifically, peanut or nut allergy — involves not exposing children under the age of three to peanut products. Allergists believe that one reason that there are so many children in the United States with peanut allergies might be the extensive early exposure they have to peanuts. Many young American children regularly eat foods that contain peanuts or peanut products.

In the case of life-threatening allergic reactions, prevention is possible only if the trigger can be completely avoided. This is difficult to do, so additional measures must be taken to control symptoms. If a person has had an anaphylactic allergic reaction in the past, a physician might suggest carrying a supply of epinephrine at all times.

Regardless of whether the trigger is or is not known, the symptoms certainly are. Having a supply of a medication that can offer immediate relief will help get the symptoms under control until the person can be taken to a hospital. Since this medication is given in the form of an injection, the person who carries it must know how to administer it. However, because there is a possibility that the person having the reaction might be incapable of completing the injection, a companion should also know how to administer it. Another measure that can help save the life of a person known to have anaphylactic reactions is even easier to do: Have the person wear a medical bracelet that indicates to medical personnel and others the nature of the person’s allergic condition and any possible triggers.

Nasal congestion is a common complication of allergic rhinitis. Congestion resulting from initial allergen exposure is usually limited; generation of other inflammatory mediators (e.g., leukotrienes) contributes, however, to the prominence of congestion in the late-phase inflammatory response period.^. Consequently, many patients will require a decongestant in addition to antihistamine therapy. Decongestants are also useful in clearing nasal passages at the onset of intranasal corticosteroid therapy to improve drug delivery.

Decongestants exert their effects by activation of alpha-adrenergic receptors in the vascular smooth muscle of the respiratory mucosa, thereby causing vaso-constriction in the turbinates. Oral formulations such as pseudoephedrine and phenylpropanolamine are available alone or in combination with various antihistamines. Decongestants may produce unwanted side effects, such as excitation of the central nervous system (e.g., insomnia, restlessness, agitation), tachycardia, urinary retention, and elevations in blood pressure. These agents should be administered cautiously in patients with hypertension, hyperthyroidism, diabetes mellitus, cardiovascular disease, or urinary obstructive diseases.

Topical decongestants (e.g., oxymetazoline, xylometazoline) [Nasal] can rapidly improve symptoms with minimal systemic effects. However, overuse may lead to the development of rhinitis medicamentosa (rebound congestion associated with nasal hyperreactivity, mucosal swelling, and tolerance). For this reason, topical decongestants are contraindicated for chronic nasal congestion, and their use should be limited to 3 to 5 days of therapy.