Drug Allergy: Causes, Symptoms & Treatment

If drugs or medications lead to undesirable side effects, a drug allergy, drug allergy or drug exanthema may be behind it. In this case, the body reacts very sensitively to certain drug ingredients, which is shown by an allergic skin rash.

What is a drug allergy?

Basically, any drug can trigger a drug allergy. However, some drugs are much more likely to cause allergic reactions. For example, allergy occurs in ten percent of all penicillin treatments, while allergies to the heart medication digoxin are very rare. By definition, the term drug allergy or medication allergy describes the increased reaction of the immune system to ingredients of drugs. The inflammatory skin rash, also called drug exanthema, originates from the connective tissue of the vessels and usually recedes. The drug rash can occur on individual parts of the body as well as distributed over the entire body. In addition to the skin reaction, any other form of allergic reaction is also possible in the case of drug allergy, since drugs also contain excipients, such as flavoring and coloring agents, stabilizers or fillers, in addition to the ingredient or active ingredient. For this reason, a drug allergy may also be due to the excipients it contains.

Causes

The underlying cause of drug allergy is a dysregulation as well as an excessive defense reaction of the immune system to certain drug ingredients or excipients. Active ingredients in, for example, psychotropic drugs, painkillers, antibiotics, or thyroid medications are often the cause of a drug allergy when used internally. But also with a local application, for example by a local anesthesia, can be causal for a drug allergy. Preservatives in a drug, such as thiomersal or benzalkonium chloride, may also be a cause.

Symptoms, complaints and signs

A drug allergy can basically occur with any drug, but is more common if the drug is taken for a longer period of time. This can result in various symptoms. In more severe cases, the body can react very violently a short time after ingestion, with shortness of breath and cardiovascular problems, up to and including anaphylactic shock, which is life-threatening for those affected. The most common form of drug allergy is a reddish skin rash with small pustules or eczema (drug exanthema), which can be very itchy; very itchy wheals can also form on the skin (hives). In some people, the mucous membranes may swell and they react with sneezing and runny nose. There may also be swelling and rashes around the mouth. With eye drops, eyes may react with redness and increased tearing. Gastrointestinal problems and nausea are also possible, as are headaches and a general feeling of illness. In the case of such symptoms, a doctor should always be consulted, because it is possible that a medication is tolerated for a long time without any problems, but at some point the body reacts with an allergy. The package inserts contain information about possible allergies.

Course

The severity of symptoms in drug allergy can vary. As a result of drug therapy, allergic symptoms may include hives, inflammatory skin rash, water– or blood-filled blisters, blotchy skin redness, or contact dermatitis. The symptoms may still be accompanied with fever and poor general condition. Different medications, such as antihistamines or glucocorticoids, can be used to treat the drug allergy to relieve the symptoms. As a rule, allergic reactions to a drug are quite mild. However, the symptoms may increase with repeated contact. Then, in addition to the skin reactions, additional symptoms such as dizziness, sweating, drowsiness, urticaria, nausea, shortness of breath, swelling of the mucous membranes may manifest themselves. In this case, a circulatory collapse can also not be ruled out.

Complications

In case of drug allergy, only very limited treatment is possible.Since the patient has an intolerance to a certain substance, in most cases this intolerance cannot be eliminated directly. Many people develop a drug allergy by taking a certain drug too often or over too long a period of time. Here the body can react with allergic reactions to the ingredient. In most cases, however, a drug allergy can be circumvented. In this case, the affected person is switched to another drug. This drug should of course have the same effect, but with a different ingredient, so that the drug allergy is not triggered again or even intensified. If the same drug continues to be taken, the drug allergy will not disappear on its own and will intensify in most cases. The consequences of a drug allergy are usually rash, headache or nausea. The symptoms are very different and individual for each patient and each drug. In any case, a doctor or pharmacist should be consulted in the event of a drug allergy, as these individuals can provide assistance in switching to a different drug.

When should you see a doctor?

It is not necessary to see a doctor with a drug allergy. However, physical symptoms that are clearly related to the medication should be discussed with a doctor. In most cases, a change to another medication is sufficient to stop further allergic reactions. Medical advice is needed at the latest if the allergic reactions affect the general well-being and, for example, cause severe physical or psychological reactions. Anyone who is unsure should consult a doctor – this is advisable at the latest in the event of panic attacks or anxiety. If severe symptoms such as swelling, edema or fever occur, a visit to the hospital is recommended. To enable rapid treatment, the responsible medication should always be carried. In the event of severe symptoms, the emergency physician must be called. If, for example, there are circulatory problems or a high fever, this may be a pronounced allergic reaction, which must be treated medically in any case. First aid measures may have to be carried out until the arrival of the rescue service.

Treatment and therapy

As a rule, to establish a diagnosis of drug allergy, the drug presumably responsible is discontinued. If symptoms improve after discontinuation, this is considered an indication of drug allergy. However, the diagnosis is made more difficult if the affected person has to take several medications. Here it is rarely possible to find the origin of the drug allergy. If skin rashes occur in the context of taking medication, a physician should be consulted in any case for clarification. A classic allergy test is only suitable to a limited extent for establishing a diagnosis, since this test can only detect an allergy caused by anti-inflammatory drugs or antibiotics. Diagnosis may also be complicated if the drug allergy mimics other diseases. Thus, it is difficult to correctly assign the reactions triggered by the allergy. In addition, it can also happen in this case that an allergy remains unrecognized as the cause here. If the medication is discontinued after consultation with the physician, the drug allergy usually takes a favorable course. In most cases, the rash heals within a few days. The prognosis is somewhat less favorable if the allergic reaction of the body is very strong. Here, a final healing can take up to six weeks.

Outlook and prognosis

Drug allergies usually have a good prognosis because they are usually triggered by certain active ingredients in a drug that can cause a rash (drug exanthema), for example. A skin rash associated with taking a drug may be the first indication of an allergic reaction. It usually disappears quickly when the allergy-causing drug is discontinued or a switch is made to a different combination of active ingredients. It becomes somewhat more difficult if the allergic reaction is more severe and the general condition worsens as a result, perhaps in combination with fever, edema or swelling. In this case, an examination in the hospital is advisable.High fever and circulatory problems in response to a drug are always a case for the emergency physician. The outlook is also somewhat less favorable if various drugs are being taken, making diagnosis more difficult. Sometimes the symptoms of a drug allergy resemble those of other diseases, making it difficult to find the exact cause. Mild allergic reactions, such as a skin rash, usually improve immediately a few days after stopping the allergy-causing drug; more severe allergic reactions may take several weeks to resolve. To improve prognosis, patients should inform their physician early in the event of intolerance reactions.

Prevention

Drug allergy cannot be prevented because the body can develop an allergy to any substance or ingredient. If allergic reactions from medicines have occurred before, it is recommended to inform the doctor about it. In case of self-medication of non-prescription drugs, the pharmacist should also be informed. In addition, it is important to carry an allergy passport in case of drug allergy. This should list the incompatible medications and may even be life-saving in emergency situations.

Follow-up

Drug allergy is not curable. To avoid discomfort, the patient must discontinue the drug in question and not take it in the future. This will prevent recurrence of the condition. This requires a high degree of personal responsibility in everyday life. Aftercare basically aims to prevent complications from occurring in the first place. This is done in the context of a drug allergy by means of the knowledge transfer described above. This is especially important in life-threatening situations. Since treatment takes place within a few minutes, such knowledge can be vital. An allergy-intolerance passport also helps if the patient is no longer responsive. It literally saves lives. Allergy sufferers can usually carry it around in their wallet. A comparison with another disease once again shows the fundamental difference. After a cancer illness regular follow-up examinations take place, by which a renewed outbreak is to be prevented. Since a drug allergy is present all the time, this procedure is not effective in this case. Protection from dangerous consequences can only be achieved by avoiding any substances.

This is what you can do yourself

Drug allergies cannot be prevented in every case or only to a limited extent. In principle, the body can develop an allergy to any ingredient or substance in a drug. However, this intolerance often only occurs when certain drugs have been consumed over too long a period of time or with too much intensity. To avoid such allergies, medications should only be consumed by the affected person if this is absolutely unavoidable. This applies especially to the excessive consumption of painkillers. Should an allergic reaction to a product nevertheless occur, a change, to a medication with other ingredients, can provide relief. If the patient is already aware of previous allergic reactions, the attending physician should be informed about them. In the case of self-medication with non-prescription remedies, the pharmacist should also be informed. In addition, it is important that those affected carry an allergy passport with them. This should list the incompatible drugs or substances. In an emergency, carrying such a passport can help the attending physician take appropriate countermeasures more quickly and can therefore be lifesaving.