A drug allergy happens when a patient's body responds to the drug administered to treat an ailment as if it would to a foreign substance, triggering the immune system to generate antibodies to fight the drug. Most of these adverse reactions appear as skin rashes or irritations, hives or swelling, mostly in the face or hands. Adverse drug reactions, or ADRs as they are called in medical parlance, usually happen when there is an overdose or indiscriminate self-medication. Sometimes, it happens when the patient is taking multiple drugs, wherein one drug reacts with another adversely.
Dr. Jerry Schier, board-certified allergist of the George Washington School of Medicine says that true allergies are rare, although most people experience adverse reactions to drugs at some point in their lives. Though most of these adverse drug reactions can be quite harmless, some of them can be life threatening like anaphylactic shock or loss of consciousness.
Common Symptoms of Drug Allergies
Some of the usual symptoms of the adverse reactions to drugs can be:
- Rashes
- Hives
- Swelling in the hands and face and fever
- Constipation or diarrhea, along with gastric problems
Severe reactions in some rare cases can include loss of consciousness, anaphylaxis, stomach cramps, or breathing difficulties, usually due to a swollen larynx. Coughing, wheezing and a runny nose can also be contraindications of some drugs. Most drug reactions are not allergic reactions and so do not involve the immune system. Some of the most severe adverse drug reactions can be skin blisters which peel, and lead to toxic epidermal necrolysis, which can be fatal if left untreated.
Allergy Causing Drugs
Most drug-induced allergies are caused by drugs like antibiotics and similar preparations. Some of the drugs that could induce allergies are:
- Penicillins like ampicillin, amoxicillin, and nafcillin can be allergic to many people, leading to paralytic attacks and fatalities if not treated immediately.
- Aspirin, ibuprofen, and other such non-steroidal anti-inflammatory drugs (NSAIDs).
- Sulfur-based compounds called sulfa drugs.
- Insulin and barbiturates.
- Vaccines.
- Anticonvulsants.
- Drugs that treat hyperthyroidism.
Allergy to one generic drug might be an indication of allergy to other similar drugs. People with AIDS or lupus can be quite allergic to many drugs. Though the allergic reactions may not be severe, they can make treating the ailment very tricky and difficult.
Another group of people who are prone to having adverse reactions to drugs are those suffering from asthma. They can have adverse reactions to even common medicines like aspirin or ibuprofen, though not very severe ones.
Diagnostic Tests for Drug Allergies
Any adverse reaction will be immediately evident, so you should consult your doctor immediately in case you feel any abnormal reactions to new medication. An allergist might need to be consulted to work out the cause behind the symptoms and to identify the allergens. In case you notice anything amiss when starting on a new medication, start maintaining a log of the dosage, the symptoms, and the severity; then consult an allergist right away to know whether you are suffering from an allergic reaction to the drug or not. Maintaining a log can be of immense help in diagnosing the allergy. The allergist might ask you to take a skin test, a blood study, or a drug-provocation test depending on the medication and the symptoms experienced. Skin tests are available only for a limited number of drugs. Therefore, if the patient has to be treated with a drug which might be an allergen, then the drug-provocation test has to be done, but strictly under medical supervision, as there can be serious adverse side effects, including anaphylaxis.
Treatment of Drug Allergies
Mostly minor allergies can be treated with antihistamines. You may have to stop taking the medication immediately and try alternate treatment or therapies. Serious reactions may necessitate corticosteroids which should be taken only under medical supervision. Extreme cases like anaphylaxis require emergency medical intervention or else it can lead to fatalities. The best way to deal with drug allergies is to de-sensitize the patient to improve tolerance so that the initial problem can be treated with the drug.
In case you experience any adverse reactions to drugs, immediate medical intervention is warranted. Do not self-medicate in such cases, as you might be exacerbating the problem or overdosing yourself.
