Drug Allergies/Sensitivities Health Article

Mild allergies/sensitivities

Drug allergies and sensitivities most often are treated by discontinuing the medication and replacing it with an alternative one. Mild symptoms usually disappear within a few days after discontinuation of the drug. Hives usually disappear within a few hours. Itchy rashes and hives may be treated with over-the-counter products such as oral antihistamines. Occasionally topical corticosteroid drugs are applied to the skin. Angioedema can take hours or days to subside; however, the swelling can be reduced with a corticosteroid or antihistamine.

Severe reactions

Severe immediate reactions occurring within one hour of drug administration, accelerated reactions occurring one to 72 hours after drug exposure, and late reactions (including rash, serum sickness, or fever) that develop more than 72 hours after drug exposure are all treated as follows:

• discontinuation of all nonessential suspect drugs
• antihistamines for hives and rashes
• oral corticosteroids for inflammation

Severe angioedema requires an immediate injection of epinephrine (a form of adrenaline) and further observation in a hospital.

Anaphylaxis requires an immediate injection of epinephrine into a thigh muscle. Epinephrine opens the air passageways and improves blood circulation. Intravenous fluids and injections of antihistamines or corticosteroids such as hydrocortisone also are administered. Cardiopulmonary resuscitation (CPR) and intubation may be necessary.

An asthma attack that is triggered by aspirin or other medications can be relieved by quick-relief or rescue medications. These include:

• epinephrine
• short-acting bronchodilators such as albuterol, proventil, ventolin, or xopenex
• prednisone for all moderate to severe reactions

Desensitization

Desensitization or immunotherapy sometimes is used by an allergy/immunology specialist to treat drug allergies to insulin, penicillin, or other antibiotics. Small amounts of the drug are injected or swallowed over a period of hours or a few days or in slowly increasing doses, to reduce sensitivity. Once antibiotic desensitization has been achieved, the full course of antibiotic treatment is followed. The procedure must be repeated if the drug has been discontinued for more than 72 hours.

Sometimes desensitization is used for non-IgE-mediated drug reactions. Desensitization may take up to a month for the following:

• aspirin
• alloprinol
• gold
• sulfamethoxazole
• sulfasalazine

Prognosis

Mild symptoms of a drug allergy usually disappear without treatment within a few days of discontinuing the drug. Although children may lose their sensitivity to penicillin, if the reaction was urticarial or anaphylaxis, they are not re-challenged with the drug for safety reasons (i.e. it is not possible to predict who has lost sensitivity). In rare cases drug allergies may cause severe asthma attacks, anaphylaxis, or death.

Prevention

Drug allergies are unpredictable because they occur after a child has been exposed to the drug one or more times. The major prevention for known drug allergies and sensitivities is to avoid those drugs and to inform all physicians, hospital personnel, and dentists of the allergies or sensitivities before treatment. In the case of a serious drug allergy, the child should wear a medical alert necklace or bracelet or carry a card (Medic-Alert and others) at all times to alert emergency medical personnel.

Children with allergies or sensitivities to aspirin should avoid all aspirin-containing drugs. Such children usually can tolerate acetaminophen and non-acetylated salicylates such as sodium salicylate and salsalate.

If a child is allergic to a drug for which there is no substitute, sometimes the dosage can be reduced to prevent an allergic reaction. If the allergy is mild and the drug cannot be discontinued, the physician may decide to pretreat the allergy, with an antihistamine such as diphenhydramine or a corticosteroid such as prednisone, before the drug is administered to reduce or eliminate the allergic reaction. The physician also may "treat through" the allergy by prescribing antihistamines and corticosteroids during drug administration.

Some disorders cannot be diagnosed without the use of radiopaque dyes. Special dyes that reduce the risk of an anaphylactoid reaction can be used. Children at risk for reaction to such dyes may be premedicated with anti-histamines and corticosteroids alone or in combination with beta-adrenergic agents before the dye is injected. Premedications include the following:

• prednisone
• diphenhydramine
• ephedrine