Drug Eruptions
Skin rashes triggered by medications
Quick Facts
- Type: Medication-related skin reaction
- Range: Mild rash to life-threatening reaction
- Common triggers: Antibiotics, anticonvulsants, NSAIDs
- Key step: Identify and stop the responsible drug
Overview
A drug eruption is a skin reaction caused by a medication. These reactions are among the most common side effects of medicines and can occur with prescription drugs, over-the-counter products, and supplements. Most drug eruptions are mild, appearing as an itchy, spotty rash that fades after the medicine is stopped.
However, a small number of drug reactions are severe and can be life-threatening, involving widespread skin peeling, blistering, swelling, or damage to internal organs. Because the same medication can cause anything from a mild rash to a dangerous reaction, it is important to recognize warning signs and seek prompt care. Stopping the responsible drug, under medical guidance, is usually the key first step.
Symptoms
Symptoms vary widely depending on the type of reaction. Mild reactions are by far the most common.
- A red or pink spotty rash, often spreading over the trunk and limbs
- Itching
- Hives (raised welts) in some reactions
- A fixed patch that returns in the same spot each time the drug is taken (fixed drug eruption)
Warning signs of a severe reaction include skin pain, blistering or peeling, sores in the mouth, eyes, or genitals, facial or tongue swelling, widespread redness, fever, and feeling very unwell. Trouble breathing, throat swelling, or fainting suggest a dangerous allergic reaction. Any of these require emergency care.
Causes
Drug eruptions occur when the immune system reacts to a medication, or when a drug irritates the skin through other mechanisms. Many medicines can be responsible, but some are more frequently involved:
- Antibiotics: Such as penicillins and sulfonamide drugs.
- Anticonvulsants: Certain seizure medications.
- Anti-inflammatory drugs (NSAIDs).
- Allopurinol and some other medications.
Reactions can appear days to weeks after starting a drug, or sometimes after it has been taken for some time. Some reactions are true allergies, while others are non-allergic. Sun exposure can also combine with certain drugs to cause a rash.
Risk Factors
- Taking multiple medications
- A previous reaction to the same or a related drug
- Certain infections, which can increase the chance of a rash with some antibiotics
- A weakened immune system
- Certain genetic factors that raise the risk of severe reactions to specific drugs
Diagnosis
Diagnosis relies on linking the rash to a medication and assessing how serious the reaction is.
- Medication history: Reviewing all drugs and supplements and their timing relative to the rash is central.
- Skin examination: The pattern and features of the rash help identify the type of reaction and any warning signs.
- Checking for severe signs: Looking for skin peeling, mucous membrane involvement, fever, and organ symptoms.
- Tests: Blood tests or, occasionally, a skin biopsy may be used to assess severe reactions and rule out other causes.
Identifying the culprit drug is essential so it can be stopped and avoided in the future.
Treatment
Treatment depends on the severity of the reaction and always involves addressing the responsible medication.
- Stopping the drug: The suspected medication is discontinued under medical guidance; do not stop essential medicines without advice unless the reaction is clearly serious.
- Soothing mild rashes: Antihistamines for itching, moisturizers, and sometimes topical corticosteroids.
- Severe reactions: Require urgent hospital care, which may include fluids, wound and eye care, and treatment of organ involvement.
- Documenting the allergy: Recording the drug so it can be avoided in the future and noting it on medical records and alert bracelets.
Most mild eruptions clear within days to weeks after the drug is stopped.
Prevention
- Keep an up-to-date list of medications that have caused reactions
- Tell every clinician and pharmacist about your drug allergies
- Wear a medical alert bracelet if you have had a serious reaction
- Avoid the responsible drug and closely related medicines in the future
- Take only necessary medications and follow dosing instructions
- Report any new rash that starts after beginning a medication
When to See a Doctor
Contact a clinician if a rash develops after starting a new medication, even if it seems mild, so the cause can be identified. Seek emergency care or call emergency services for warning signs of a severe reaction:
- Skin blistering, peeling, or pain, or widespread redness
- Sores or swelling of the lips, mouth, eyes, or genitals
- Facial or tongue swelling, trouble breathing, or throat tightness
- Fever, feeling very unwell, or a rapidly spreading rash
Frequently Asked Questions
How soon after starting a drug does a rash appear?
Mild drug rashes often appear within days to a couple of weeks of starting a new medication, though some reactions occur sooner or after a drug has been taken for a while. Knowing the timing of all your medicines helps a clinician identify the cause.
Which medications most commonly cause drug eruptions?
Antibiotics such as penicillins and sulfonamides, certain anticonvulsants, anti-inflammatory drugs, and allopurinol are among the more frequent causes. However, almost any medication can trigger a reaction in a susceptible person.
When is a drug rash an emergency?
Seek emergency care if there is skin blistering or peeling, sores in the mouth, eyes, or genitals, facial or tongue swelling, trouble breathing, fever, or feeling very unwell. These can signal a severe, life-threatening reaction that needs immediate treatment.
What should I do if I think a medicine caused a rash?
Contact a clinician promptly to confirm the cause. Do not stop essential medications on your own unless the reaction is clearly serious, in which case seek urgent care. Once a culprit drug is identified, it should be recorded and avoided in the future.
Can I take the same drug again after a drug eruption?
Usually not. If a medication has caused a reaction, it and often closely related drugs should be avoided, and the allergy should be documented in your records. Re-exposure can cause a faster or more severe reaction, so always inform your clinicians and pharmacists.
References
- American Academy of Dermatology (AAD). Drug reactions.
- MedlinePlus, U.S. National Library of Medicine. Drug reactions.
- U.S. Food and Drug Administration (FDA). Drug allergies.