Allergy to Drugs

What is drug allergy?

No medicine is 100% safe to all individuals in all circumstances. A drug allergy is a specific type of reaction involving the immune-system cells. In this, a person’s immune system mistakes a medication for a disease-causing agent.

The immune system becomes sensitized on taking the allergy-causing drug for the first time or first several times; and ready to react when next taken the drug. After being sensitized, the immune system churns out immunoglobulin E (Ig E) antibodies tailor-made to recognize the drug. These antibodies trigger the release of inflammatory chemicals which cause the allergy.

Penicillin and related antibiotics are the most common cause of drug allergies. Other common allergy causing drugs include sulfa drugs, anticonvulsants, insulin preparations, local anesthetics, and iodine.

How to detect a drug allergy?

Sometimes only a single first dosage of a drug is required to sensitize the immune system. At times, the person may be fully cured after taking the entire dose of the medication without any problem, only to break out in an allergy on taking the drug again a year later.  Also, if one is sensitized to a particular drug, he might develop a drug reaction to a related drug also.

Typical signs and symptoms of an allergy -

• Rashes with mild to severe itching
• Nausea, vomiting, diarrohea
• Fatigue
• Drowsiness or insomnia
• Facial swelling
• Difficulty breathing, wheezing
• Rapidly falling blood pressure
• Irregular heartbeat
• Abnormal bleeding
• Kidney damage
• Liver damage
• Skin reactions ranging from mild rashes to flaming red patches of hives.

Treatment –

There is no known way to prevent development of a drug allergy. In people who have a known drug allergy, avoiding the medication is the best means to prevent an allergic reaction.

The treatment goal is to relieve symptoms and prevent a severe reaction, which can also be fatal at times.

• Antihistamines are prescribed which relieve mild symptoms (rash, hives, itching).
• Topical corticosteroids may also be recommended. Bronchodilators may be advised to reduce asthma-like symptoms (moderate wheezing or cough).
• Epinephrine injections may be necessarily prescribed in certain cases to treat anaphylaxis.
• Penicillin allergy at times responds to immunotherapy in which increasing doses of the drug are given to improve tolerance to the drug. Desensitisation may occasionally be advised for other antibiotics - for example, sulphonamides, cephalosporins, but strictly under medical supervision.

Precautionary steps to avoid drug allergy –

• Before taking a new medication or a drug, ask the doctor if you could be allergic to it. If you've had a previous reaction to any drug, you need to be all the more careful.
• Once you know you have a drug allergy, avoid the drug and related agents.
• If one has a history of previous allergy to drugs, he can go for a skin test to find out for certain. However, tests for most drug allergies are generally not much reliable. Skin testing may confirm allergy to penicillin-type medications only.
• If you develop allergy like symptoms shortly after taking medication, consult your doctor. You can take an antihistamine available over the counter to relieve itching.
• More severe reactions may require immediate medical treatment with oral or injected corticosteroids.

Some simple home remedies:

• Grind 1 tablespoon of poppy seeds with one teaspoon water. Add one teaspoon limejuice. Apply to affected area for relief from the allergy.
• Add 1 teaspoon limejuice with sandalwood paste. Apply to affected skin allergy area.
• Vitamin C is very helpful in fighting off the allergic reactions.
• Avoid white sugar, and everything made with it. The process of chemically whitening sugar is toxic.
• Regularly practice juice fasting. This will cleanse your system of toxins and residues.
• Avoid smoking and heavy alcohol consumption. Heavy coffee consumption is also to be avoided.
• Drink lots of water – 8/10 glasses daily atleast.

Risk factors for drug allergy -

Adverse drug reactions occur mainly in young and middle aged adults and are twice as common in women as compared to men.

Genetic factors may be important, that is those with a family predisposition.

An allergic reaction is also quite dependent on the route of administration; it occurs most commonly with the local route, less commonly with the parental route, and least often with the oral route. Intravenous administration gives rise to the more severe type of reactions.

Patient related-

Age, sex, genetics, atopy, immune system related diseases such as AIDS

Drug related

• Macromolecular size, bivalency, route of administration, dosage, duration of treatment
• Aggravating factors
• Blockers, asthma, pregnancy

Which drugs cause allergies?

Although any drug can cause an allergic reaction, antibiotics are the most common source of drug-related allergies. Some examples of drugs that have an increased risk of causing allergic reactions include.

• Antibiotics
• Penicillin class drug, ampicillin
• Sulfa drugs
• Anticonvulsants
• Insulin