Drug eruption
and Martina Feichter, medical editor and biologistClemens Gödel is a freelancer for the medical team.
More about the expertsMartina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.
More about the experts All content is checked by medical journalists.
The drug eruption is an allergic or pseudo-allergic skin reaction to a drug. The most important indication of this is the temporal relationship between the use of the medication and the rash. With the exception of severe allergic reactions and those that affect the entire body, symptoms usually resolve without lasting damage after stopping the drug. Read more about symptoms, diagnosis and treatment of drug eruptions here!
ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. L27
Drug eruption: description
The drug eruption ("drug rash") is an allergic or pseudo-allergic skin rash caused by an internal or external drug. It is one of the most common drug side effects.
In most cases, drug eruptions are caused by antibiotics, especially penicillins. For example, a pseudoallergic rash (ampicillin rash) can develop during treatment with ampicillin. Other groups of drugs that can cause a drug eruption include anti-inflammatory pain relievers from the NSAID group (such as ASA, ibuprofen, diclofenac) and drugs for epilepsy and gout.
Most of the time, it is the drug substance itself that is responsible for a drug eruption. Auxiliary substances in the drug, such as preservatives, flavorings, colorings or fillers, are less likely to trigger the rash.
In an allergic drug eruption, the overreaction of the immune system can be so extensive that the skin changes are accompanied by symptoms that affect an entire organ system or the entire body (systemic symptoms). These include, for example, nausea, vomiting, diarrhea, swelling of the mucous membranes and cardiovascular disorders.
Drug eruption: symptoms
A drug eruption can occur on almost any part of the body, including the area of the mucous membranes. Typically, however, it develops on the extremities (arms, legs) and trunk (chest, stomach, back). Sometimes the drug eruption spreads from the trunk; in other cases it extends from the extremities to the trunk of the body.
Appearance
The drug eruption is a very diverse skin phenomenon. It can easily be confused with the large-spotted rash in measles, with the small-spotted rash in rubella, or with the skin changes in scarlet fever or syphilis.
In most cases, the drug eruption appears as a reddish elevation, often similar to a mosquito bite. Wheals (urticaria) are also a common symptom of drug eruptions. Sometimes large bubbles form, which burst (bullous shape).
So the type of rash does not tell with certainty whether it is a drug eruption or not. In addition, a drug rash can vary in severity - sometimes it is only light and small. In severe cases, the skin can peel off over a large area and die off.
More symptoms
In more serious cases, an allergic drug eruption is accompanied by other symptoms such as diarrhea, nausea, vomiting and swelling of the mucous membrane in the mouth and throat. This is associated with a more or less pronounced feeling of illness, occasionally with a fever. Additionally, nearby lymph nodes can swell. If the allergic reaction is very severe, the cardiovascular system is also affected.
Special forms of drug-induced rash
Fixed drug eruption
The so-called fixed drug eruption develops 30 minutes to eight hours after taking a drug in the vicinity of the joints or on the mucous membranes, in the form of single or multiple, coin-sized reddish spots. When you stop taking the drug, these spots often persist for months or years. In many cases, they turn dark brown.
A fixed drug eruption can be triggered, for example, by antibiotics of the tetracycline type or by barbiturates (sedatives and sleeping pills).
Toxic pustoloderm
Another special form of drug-related skin reactions is toxic pustoloderm (acute generalized exanthemic pustulosis, AGEP). Suddenly red discolouration with pustules appear, which can resemble psoriasis. Typically, the pustules are located in the crooks and the spaces between the fingers and toes. The rash may burn or itch.
Erythroderma
With erythroderma, the whole skin on the body is reddened. In addition, other symptoms such as fever, swelling of the lymph nodes and a poor general condition are possible. In extreme cases, life can even be in danger! However, erythroderma is not always caused by drugs. Skin diseases are more often the cause.
Erythema exudativum multiforme
The erythema exudativum multiforme is a sudden, circular, oozing and bright red skin reaction triggered mainly by infections and medication. Mostly it shows up on the extensor sides of the hands and arms, sometimes also on the mucous membranes. The general condition of the affected patients can also be severely impaired.
The strongest forms of erythema exudativum multiforme are toxic epidermal necrolysis (TEN / Lyell syndrome) and Steven Johnson syndrome (SJS). However, these are rare. Large areas of skin loosen here and die. The mucous membrane, including the conjunctiva of the eye (conjunctivitis), is also affected. The skin lesion resembles a second-degree burn.
In Steven Johnson Syndrome, less than ten percent of the skin is affected, and more than 30 percent in toxic epidermal necrolysis. In addition to the strong skin reaction, both are also noticeable in symptoms of the liver, intestines and lungs as well as fever.
Other special forms are vascular inflammation (vasculitis), erythema annulare centrifugum (slightly scaling skin changes), pruritus sine materia (itching without a rash), angioedema and allergic contact eczema. The so-called "EGFR inhibitor rash" can occur during cancer treatment with certain drugs.
DRESS syndrome
In the rare drug reaction called DRESS syndrome, a flat skin rash forms one to eight weeks after using the triggering drug, often accompanied by inflammation in the kidneys, liver, thyroid, blood cells or nerve tissue, as well as high fever and facial swelling.
Drug-Induced Lupus
In the case of drug-induced lupus erythermatosus, symptoms similar to those of the rheumatic disease lupus erythematosus occur - triggered by a drug. A rash, joint discomfort, and a fever develop. As soon as the patient stops taking the triggering drug, however, the symptoms usually resolve.
Drug eruption: causes and risk factors
In most cases, a drug eruption is an allergic reaction to a drug. More rarely, it is not allergic, but a pseudo-allergy.
Allergic drug eruption
The immune system regards a drug as a dangerous foreign substance that needs to be fought - the result is an allergic reaction, usually of type IV. This is a delayed type allergy: It is caused by T cells (T lymphocytes) mediated, and the allergy symptoms here - in contrast to other allergy types - are delayed:
When you first come into contact with a new drug, it usually takes several hours to days for the drug eruption to develop. Sometimes weeks go by, or the drug rash does not form until you stop taking the drug. If the drug is used again later, the skin reactions usually set in earlier - often after six to 48 hours.
The first contact with a drug does not always trigger sensitization, i.e. the development of a defense reaction of the immune system. Sometimes a drug is used without problems a few times before the immune system suddenly begins to act against it.
Some factors generally favor allergic reactions to medication (for example in the form of an allergic drug eruption). These risk factors include:
- female gender
- Age between 20 and 49 years
- irregular use of the drug
- sudden increase in dose
- simultaneous occurrence of a viral infection (e.g. herpes)
- Immune system disorders
- cancer
Pseudo-allergic drug eruption
A drug rash can develop even without an allergic reaction from the immune system. For example, cortisone supplements can cause an acne-like rash. The same applies to drugs containing lithium, which are prescribed for certain mental illnesses.
Some medications make the skin more sensitive to UV rays. This applies, for example, to certain drugs against psychoses (neuroleptics) and some antibiotics (such as tetracyclines). During the treatment, the skin can therefore redden painfully (phototoxic reaction) or even react allergically (photoallergic reaction) when exposed to sunlight or in the solarium. You can read more about this in the sun allergy article.
A common form of pseudo-allergic drug rash is ampicillin rash. This rash can develop during or after treatment with the antibiotic ampicillin if certain viral infections are present at the same time - including in particular Pfeiffer's glandular fever: 30 to 70 percent of adult patients and almost all children with Pfeiffer's glandular fever develop an ampicillin rash under ampicillin therapy. After the viral infection has subsided, the antibiotic is often tolerated again without any problems.
Drug eruption: examinations and diagnosis
If you develop an unclear rash - especially (shortly) after using a new medication - you should definitely see a doctor. It is best to contact your family doctor or the doctor who may have prescribed the drug in question for you. A suitable contact person is also a specialist in skin diseases (dermatologist).
The doctor will first obtain important background information about your medical history (anamnesis) in a detailed discussion. Possible questions include:
- What prescription and over-the-counter medications are you currently using or have recently used? Is there a new preparation included?
- How did the skin reaction develop?
- Are there any other symptoms such as itching or general discomfort?
- Have you or a family member had an adverse reaction to a drug?
Since the drug eruption can be similar to a large number of other diseases, the medical consultation and thus the clarification of the connection with the use of medication are of particular importance.
After the interview, the doctor will take a closer look at the rash.
The information from the anamnesis discussion and a look at the rash are sometimes enough for the doctor to suspect a drug eruption and start treatment - among other things, to recommend discontinuing the presumably responsible drug. If the rash then improves, it reinforces the suspicion of a drug eruption.
Testing
Exact tests to detect the trigger of a drug eruption are usually only carried out after the symptoms have subsided. A skin test (patch test) is often used: a small amount of the substance (s) that may have caused the rash is applied to the patient's skin. A resulting hypersensitivity reaction of the skin on the affected area confirms the suspicion of an allergic drug eruption.
A lymphocyte transformation test (LTT) may also be done. This allergy test is carried out in vitro ("in a test tube"): In a blood sample from the patient, specific immune cells (T lymphocytes) against the suspected cause of the rash are looked for.
In unclear cases, a provocation test can sometimes be useful: the doctor specifically administers the suspected drug to the patient to see how he or she reacts to it. Under certain circumstances, this can be very dangerous if the patient develops a severe hypersensitivity reaction! A provocation test is therefore carried out under medical supervision.
Drug eruption: treatment
In general, the (presumably) triggering drug should be discontinued immediately (after consultation with a doctor!) (Unless the drug eruption is only very mild). If necessary, the doctor will prescribe a substitute drug, although he must be aware of possible cross-reactions (especially with antibiotics): The patient can also react sensitively to a substitute preparation that is chemically similar to the first drug.
Sometimes a (triggering) drug is indispensable for the treatment of an existing disease, so it must not be discontinued - even if it causes a pronounced allergic drug eruption. Then the doctor may give cortisone and antihistamines as a preventative measure to reduce the allergic reaction.
Medication
If a drug eruption is localized and itchy, an ointment with an antihistamine or cortisone can often provide sufficient relief. In more severe cases, the doctor may give cortisone or antihistamines as a tablet or infusion. In particularly threatening cases, he will consider infusing immunoglobulins.
If it is suspected that the skin previously damaged by the drug eruption has become infected with bacteria, the patient should be treated with antibiotics. Because the bacteria can spread in the tissue and in bad cases in the blood. Then there is the risk of "blood poisoning" (sepsis).
Steven-Johnson syndrome and so-called toxic epidermal necrolysis are clinical pictures that require intensive medical treatment and monitoring. They are life-threatening courses of a drug reaction, but can also have other triggers.
Desensitization
In rare cases, a so-called desensitization can be carried out. However, this is only done with extremely important drugs without substitute options (such as insulin for diabetes mellitus or certain antibiotics).
Drug eruption: disease course and prognosis
In most cases, a drug eruption resolves within a few days of stopping the offending drug. However, very severe courses such as Steven Johnson Syndrome or toxic epidermal necrolysis can be fatal. The cause of this is usually an infection that has spread through the damaged skin into the bloodstream (sepsis).
After an allergic drug eruption and the conclusion of the allergy diagnosis, the doctor should issue the patient with an allergy passport and inform him about the trigger and possible cross-reactions. Alternative medication that the doctor enters as a recommendation in the allergy passport should ideally be tested by the doctor and patient beforehand.
In any event, the patient should avoid the offending drug whenever possible. The best thing to do is to make a note of the name of the drug. B. carry it in your wallet so that doctors can be notified immediately in the event of further treatment. Because when the trigger is given again, the reaction is usually more violent than the first time.
Apart from discoloration of the skin, as in the case of a fixed drug eruption, in the vast majority of cases a drug eruption does not leave any permanent damage. Exceptions are severe courses, which can also lead to sticking of the mucous membrane.
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