Drug Rash

Medically Reviewed By William C. Lloyd III, MD, FACS

What is a drug rash?

A drug rash is a skin reaction to an ingredient in a medication. Drug rashes are the most common form of drug-induced conditions. They affect from 5 to 15% of medication courses. This includes courses of both prescription and over-the-counter medicines. Drug rashes can be either allergic or nonallergic. 

Allergic rashes are the result of the immune system reacting to the drug. These immune-related rashes are the most common type of rash from medication. About 95% of drug rashes are allergic. However, there are several different types of allergic rashes. You can have a local reaction to a drug in the form of contact dermatitis. You can also have a widespread drug allergy rash from a medicine you take by mouth or through a vein.

Nonallergic rashes are less common, but can still be problematic. These rashes include flushing, photosensitivity (increased sensitivity to sunlight), skin color changes, and irritant contact dermatitis, such as from drug patches. Symptoms vary depending on the type of drug rash. In general, drug rashes cause a change in the color or texture of the skin. This can include redness, blisters, pimples, patches, scaling, and even sloughing and peeling skin. The onset of these symptoms also varies with the type of rash. Some develop with time and others occur very soon after starting a drug.

Treating drug rashes starts with stopping the offending medicine. Sometimes, this is easy if there is a clear connection between starting the drug and developing the rash. For most mild or moderate drug rashes, oral antihistamines, corticosteroids, and other medicines will treat the symptoms.

Call your doctor as soon as possible if you have mild symptoms of a drug rash. In some cases, drug rashes can be serious and potentially life threatening. Seek immediate medical care (call 911) if you have a rash along with any of these serious symptoms:

  • Blisters on the mucous membranes of the nose, mouth, eyes or genitals

  • Dizziness, lightheadedness or fainting

  • Fast heart rate or pulse

  • Fever, joint pain, nausea, vomiting, diarrhea or abdominal cramps

  • Shortness of breath, wheezing, difficulty breathing, or tightening of the throat

  • Skin that appears scalded or detaches in sheets

  • Swelling of the eyes, face, lips or tongue

What are the symptoms of a drug rash?

Drug rashes can look very different from one to the next and range from mild to severe. Some occur within minutes or hours of starting a medication. Others take days or weeks to develop. It is even possible to get a drug rash up to a week after stopping a medicine. Symptoms may also continue to worsen after the drug is stopped.

Common symptoms that may indicate a drug rash include:

  • Color changes, including red, blue, purple or gray discoloration

  • Hotness to the touch

  • Itching

  • Pain or burning

  • Swelling and skin texture changes, including hives, wheals, welts, patches, plaques, bumps, blisters, pimples, ulcers, scaling, peeling and sloughing

Other drug allergy symptoms include a runny nose and itchy or watery eyes. Call your doctor right away if you suspect a drug rash.

Serious symptoms that might indicate a life-threatening condition

Some types of drug rashes can be life threatening. This includes rashes with symptoms of anaphylaxis and rashes that affect the entire skin surface or cause large areas of skin to peel. Losing the outer protective skin barrier can lead to infection, dehydration and shock. Seek immediate medical care (call 911) if you have a rash with any of the following symptoms:

  • Blisters in the nose, mouth or eyes, or in and around the genitals

  • Dizziness, lightheadedness or fainting

  • Fast heart rate or pulse

  • Fever, nausea, vomiting, diarrhea or abdominal cramps

  • Shortness of breath, wheezing, difficulty breathing, or tightening of the throat

  • Skin that appears scalded or detaches in sheets

  • Swelling of the eyes, face or lips

What causes a drug rash?

There are two types of drug rashes—allergic and nonallergic. An allergic reaction rash happens when the immune system encounters a drug molecule and becomes sensitized to it. It reacts to the drug by releasing histamine and other chemicals to combat what it sees as a threat. Once the immune system is sensitized, it will react every time it finds the drug. In some cases, the reaction worsens with each encounter. Common causes of allergic drug rashes include:

  • ACE (angiotensin-converting enzyme) inhibitors and beta blockers

  • Antibiotics, including penicillins, cephalosporins, fluoroquinolones, sulfonamides and tetracyclines

  • Anticonvulsants

  • Aspirin and NSAIDs (nonsteroidal anti-inflammatory drugs)

  • Contrast media like barium

Nonallergic rashes can result from irritation, increased sensitivity to the sun, and changes in skin pigmentation. There is also a form of nonallergic rash called a pseudoallergic rash. It does not involve the immune system, but looks the same as an allergic rash. It can be just as serious as an allergic rash and requires the same treatment. Common causes of nonallergic drug rashes include:

  • Adhesives in drug patches

  • Antibiotics, including sulfonamides, tetracyclines and vancomycin

  • Anticonvulsants

  • Diuretics

  • NSAIDs

  • Opiates

  • Retinoids

What are the risk factors for a drug rash?

Anyone can develop a drug rash. However, there are several factors that increase the risk including:

  • Certain medical conditions, including asthma, lupus, and HIV infection

  • Being female

  • Family history of drug rash

  • Personal history of drug rash, drug allergy, or other allergies, such as hay fever or food allergies

  • Repetitive, prolonged, or high-dose exposure to a drug

Reducing your risk of a drug rash

It is not possible to predict if you will get a drug rash or not unless you have already had one. If you have a known drug rash reaction—whether allergic or nonallergic, protect yourself by:

  • Informing all healthcare providers about your rash

  • Using one pharmacy to fill your prescriptions

  • Wearing or carrying medical alert information identifying your reaction

Drug rashes can be hard to diagnose. There are also a few very rare forms of drug rash. If you have had a serious drug reaction or have reacted to several different drugs, you could benefit from working with an allergist. These doctors have the expertise to help you protect yourself from future problems.

How is a drug rash treated?

The mainstay of drug rash treatment is stopping the drug that is causing the rash. Sometimes, this is very easy, such as a rash that starts a few days after starting an antibiotic. However, it can also be challenging. Drug rashes do not always show up with obvious timing relative to starting a drug. Some drug rashes are somewhat rare with appearances that don’t always raise suspicion of a drug reaction. It’s also common to start several drugs within a relatively short time. This makes it hard to figure out which one is the culprit. Doctors may have to methodically stop and restart drugs to find the problem.

Once the drug is stopped, symptoms generally fade over a few days to weeks. To help resolve symptoms of a mild or moderate drug rash, doctors may recommend the following treatments: 

  • Antihistamines

  • Corticosteroids, including topical agents you apply to the skin and oral dosage forms

  • Other medicines, such as montelukast (Singulair)

In some cases, doctors recommend a procedure called desensitization. It is for allergic drug rashes and reactions when it is necessary to take the offending medicine. It involves a process of increasing the dose of the drug by small increments over several hours or days. The goal is to reach the dose you need without triggering a reaction from your immune system.

In severe cases of drug rash, hospitalization is usually necessary. This includes drug rash with anaphylaxis and drug rashes that cause sheets of skin to slough off and threaten the integrity of the skin barrier.

What are the potential complications of a drug rash?

Most people recover from a drug rash without complications once they stop the triggering drug. However, anaphylaxis and severe drug rashes can be fatal or lead to serious complications. Anaphylaxis is a life-threatening allergic reaction that involves two or more organ systems. 

Severe drug rashes that involve large areas of the skin surface are also very dangerous. They can destroy the skin’s protective function. If the rash leads to skin shedding over large areas, the body loses its ability to regulate temperature and fluid balance. Life-threatening infection, dehydration and shock can occur.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Sep 11
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