What is a drug allergy?
Drug allergy is an abnormal reaction of the body to a drug substance. Any medicine is a potential allergen. Allergies can be manifested by rashes on the skin and pathology of the internal organs. The drug allergy has significant differences from the side effect of the drug.
• The development of drug allergies is associated with an excessively violent reaction of the human immune system to the drug. It can affect different organs and vary in severity. In most cases, the drug allergy flows relatively easily and affects only the skin. The most common form is a koreal-like rash consisting of small, pinhole-sized, red papules and flat spots. Usually it is accompanied by itching and appears a few days after the start of the drug. Less common, but also relatively light form is persistent drug erythema (a localized form of an allergic reaction). A few days after the beginning of taking the drug on the skin there are spots. After a few months they pass, but when they are taken again, they appear again in the same place.
Heavy forms
A more severe form of drug allergy is hives. It is characterized by severe itching and may be accompanied by edema of the eyelids and lips. In severe cases, the following can develop:
• angioedema - the most dangerous is the transition of the edema to the tongue, larynx and trachea;
• Anaphylaxis is a life-threatening condition characterized by rapid development; develops after an insect bite or a meal or medication for which there is an allergy, and may be accompanied by loss of consciousness;
• multi-form exudative erythema - a severe skin allergy, characterized by the appearance of round red spots on any part of the body. Malignant variant of multiforme exudative erythema is Stevens Johnson syndrome, manifested by the appearance of blisters and skin flaking. In the absence of timely diagnosis and treatment can lead to death.
• Coripiform rash is the most common form of drug allergy. Usually it appears a few days after the start of the drug.
All forms of drug allergy are more or less similar. About 15% of hospital patients have a risk of developing an allergic reaction to a drug. However, only 5% of these reactions will be true. Penicillin is one of the drugs most often causing allergies. About 2% of people in the world are allergic to the antibiotics of the penicillin group, although severe reactions develop quite infrequently. If the patient has an allergic reaction to any medicine, one can assume an allergy to other drugs. For example, with allergy to penicillin, there is a 10-20% risk of such a reaction to drugs from another group of antibiotics - cephalosporins.
Why does the allergy develop?
The immune system perceives the drug as foreign and triggers inflammation mechanisms that cause hives and other rashes. The development of drug allergy can not be predicted. Nevertheless, some factors increase the likelihood of its occurrence. These include:
• genetic predisposition;
• simultaneous intake of several drugs;
• According to some reports, women are more prone to allergies than men;
• a number of diseases.
Penicillin is the most common cause of drug allergy. 2% of the world's population are allergic to penicillin group drugs. When identifying a drug allergy, measures must be taken to reduce its manifestations. If the first symptoms appear, the drug should be immediately withdrawn. With hives, cold compresses and soothing lotions are used topically. Patients are advised not to take hot baths and showers, wear loose clothing. Antihistamines can reduce skin irritation. If the allergic reaction is severe, it is necessary to monitor the patient for the next 24 hours for re-reaction or deterioration. To reduce skin rashes associated with drug allergy, antihistamines are prescribed.
Repeated reactions
If the patient once had an episode of an allergic reaction to the drug, then every time you take this drug, it repeats, and it can be more and more difficult. To exclude allergies to a particular drug, the doctor can conduct tests with allergens. These include, for example, a skin test in which a very small amount of the drug is applied to the patient's skin, followed by an assessment of the response to it. However, it is not suitable for all drugs. Another method - a provocative test - involves taking a small dose of medicine under the supervision of a doctor. However, in most cases it is possible to suspect an allergy on the basis of an examination of the patient's anamnesis.
• A note on the allergy in the patient's medical history will help to avoid prescribing this medicine in the future.
• Patients are advised to take with caution the drugs dispensed in the pharmacy without a prescription, since there is a danger of developing an allergic reaction; in doubtful cases, you should consult a pharmacist or doctor.
• In severe cases, patients may be advised to wear a special bracelet that lists the names of the drugs that cause an allergic reaction.
• There is a special set of medicines in the physician's office that are needed to provide first aid for anaphylactic reaction, including epinephrine.
• In some cases, patients may undergo a course of desensitizing therapy, this is a rather unsafe procedure that should be performed only in a hospital in the presence of medical personnel who have the skills of resuscitation.