Are blisters a side effect of antibiotics?

October 12, 2025 •

4 min read

While antibiotics are a cornerstone of modern medicine, they are also a common cause of adverse cutaneous drug reactions, which in rare cases can include blistering. It is crucial to understand the different types of skin reactions, as some blistering may signal a medical emergency.

Quick Summary

Blisters are a potential, albeit rare, side effect of antibiotics, often indicating a serious allergic reaction or drug-induced sensitivity. Severe cases, like SJS/TEN, involve widespread blistering and require immediate medical care. Other reactions, such as fixed drug eruption or photosensitivity, can also cause localized blisters.

Key Points

Blisters are a rare, but possible side effect of antibiotics: While most skin reactions are mild, blistering is a sign that a more serious condition may be present.
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but life-threatening : These conditions, caused by drug reactions, involve widespread blistering and peeling of the skin and require emergency medical care.
Photosensitivity can cause blistering in sun-exposed areas: Some antibiotics, like tetracyclines, can increase the skin's sensitivity to sunlight, leading to a severe, blistering sunburn-like reaction.
Fixed drug eruption (FDE) causes localized, recurrent blistering: This reaction causes skin lesions, which can include blisters, to reappear in the same location upon re-exposure to the same drug.
Certain antibiotic classes are more commonly implicated in severe skin reactions: Sulfonamides, penicillins, and cephalosporins are frequently associated with SJS/TEN.
Immediate medical attention is crucial for severe symptoms: If you experience widespread blistering, skin peeling, or flu-like symptoms with a rash, seek emergency medical care immediately.

Antibiotics and Blistering: A Rare but Serious Connection

Although most antibiotic side effects are mild, the development of blisters is a rare but critical concern. These blistering reactions can manifest in several forms, ranging from localized and recurrent lesions to widespread, life-threatening skin detachment. Recognizing the difference between a minor rash and a severe condition is paramount for patient safety and appropriate medical intervention.

Life-Threatening Blistering Reactions: SJS and TEN

Stevens-Johnson syndrome (SJS) and its more severe form, toxic epidermal necrolysis (TEN), are rare and life-threatening drug-induced skin disorders that can be triggered by antibiotics. SJS/TEN usually begins with flu-like symptoms, including fever, body aches, and malaise, followed by a painful rash that spreads and blisters. In SJS, less than 10% of the skin is involved, while in TEN, over 30% of the body surface area is affected. The affected skin then peels off in sheets, leaving large, raw areas susceptible to infection, similar to a burn wound.

Crucially, these conditions also involve damage to the mucous membranes, affecting the mouth, eyes, and genitals. Hospitalization, often in a burn unit, is required to manage the condition and minimize complications. A meta-analysis has shown that antibiotics are responsible for over one-quarter of SJS/TEN cases worldwide, with sulfonamides, penicillins, and cephalosporins being among the most common culprits.

Photosensitivity Reactions and Blisters

Certain antibiotics can increase the skin's sensitivity to sunlight, a condition known as photosensitivity. This reaction can cause an exaggerated sunburn with blistering in sun-exposed areas. The specific antibiotic class involved often determines the likelihood and severity of this reaction. For example, tetracyclines, particularly doxycycline, are well-known to cause drug-induced photosensitivity. If this occurs, patients should avoid direct sunlight, use sun protection, and consult their doctor.

Fixed Drug Eruption (FDE)

Fixed drug eruption is an adverse reaction characterized by one or more localized, well-demarcated skin lesions that recur in the same spot each time the patient is exposed to the offending drug. These lesions can manifest as a dusky red or purplish patch that may eventually form a blister. While generally less severe than SJS/TEN, bullous (blistering) FDE can be significant and cause pain or a burning sensation. Many antibiotics, including sulfonamides, tetracyclines, and amoxicillin, have been implicated in causing FDE. The condition resolves upon discontinuation of the medication, though residual hyperpigmentation can last for months.

Other Rare Blistering Disorders

In addition to SJS/TEN, photosensitivity, and FDE, antibiotics can, in rare cases, trigger other bullous disorders. Drug-induced pemphigus, for instance, can be caused by antibiotics such as penicillin, cephalosporins, and vancomycin, leading to blistering that may persist even after the drug is withdrawn. Drug-induced linear IgA bullous dermatosis (LAD) is another possibility, sometimes caused by medications like vancomycin, amoxicillin, and ampicillin-sulbactam. These autoimmune reactions involve autoantibodies targeting skin proteins, resulting in blistering.

What to Do If Blisters Appear

If you develop blisters after starting an antibiotic, contact your healthcare provider immediately. Do not stop taking your medication without consulting them unless the side effects are severe. A medical professional can help determine if the blistering is related to the antibiotic and whether it indicates a serious problem. In cases of severe blistering, flu-like symptoms, or mucosal involvement, seek emergency medical care. The immediate withdrawal of the culprit drug is crucial for improving outcomes in severe cutaneous reactions like SJS/TEN.

Comparison of Mild vs. Severe Antibiotic-Induced Skin Reactions


Feature	Mild Maculopapular Rash	Severe Blistering Reactions (e.g., SJS/TEN)
Appearance	Flat, red, non-blistering spots or slightly raised bumps.	Painful rash that spreads and develops into blisters or peeling skin.
Onset Time	Can be delayed, often appearing 5-7 days after starting the antibiotic.	Can appear hours to days after exposure, or delayed by weeks.
Symptoms	Itchy, but generally no systemic symptoms.	Often starts with flu-like symptoms like fever, fatigue, and sore throat.
Location	Often on the chest, back, and abdomen, spreading to limbs.	Widespread, often involving the face, eyes, mouth, and genitals.
Urgency	Non-allergic types may not require stopping the medication, but doctor consultation is advised.	Medical emergency requiring immediate hospitalization and drug discontinuation.

Conclusion

While blisters are not a common side effect of antibiotics, they can be a warning sign of a serious allergic reaction or drug-induced skin condition. The spectrum of blistering reactions includes fixed drug eruptions, photosensitivity, and the life-threatening Stevens-Johnson syndrome and toxic epidermal necrolysis. Prompt recognition of severe symptoms, such as widespread blistering, skin peeling, and mucosal involvement, is critical for obtaining timely medical treatment. Anyone who develops blisters while on an antibiotic should contact their healthcare provider immediately. For more in-depth information on severe cutaneous drug reactions, refer to resources from authoritative sources such as the National Institutes of Health.

Frequently Asked Questions

You should contact your healthcare provider immediately if you develop any kind of rash or blisters while on antibiotics. While mild rashes may not require stopping the medication, blisters can signal a more serious problem, and a doctor's guidance is essential.

A mild rash is typically a flat, red, and itchy rash without blisters, though some allergic hives may involve swelling. A severe reaction, like SJS/TEN, involves a painful, spreading rash with widespread blistering and flu-like symptoms. If you are unsure, it is best to consult a doctor.

Sulfonamides, penicillins, and cephalosporins have been frequently associated with severe blistering conditions like SJS/TEN. Tetracyclines are also known to cause photosensitivity reactions with blistering in sun-exposed areas.

SJS often begins with flu-like symptoms, including fever, fatigue, and a sore throat, followed by the development of a painful rash that spreads and blisters. It is a medical emergency requiring immediate hospitalization.

Treatment depends on the severity and cause. Mild blisters from photosensitivity or fixed drug eruption may be managed with supportive care, such as topical steroids and moisturizers, and discontinuing the offending drug. Severe conditions like SJS/TEN require immediate hospitalization, often in a burn unit, and discontinuation of the drug.

A fixed drug eruption (FDE) is a reaction that causes one or more localized lesions, which can be red patches or blisters, to recur in the exact same spot on the skin each time the specific medication is taken.

If you experience a severe blistering reaction, you should permanently avoid the causative drug and potentially structurally related drugs from the same class. Always inform all healthcare providers of your specific antibiotic allergy.