Can Nitrofurantoin Cause Blisters? Understanding the Risks and Side Effects

October 12, 2025 •

4 min read

In clinical trials, allergic reactions to nitrofurantoin occurred in less than 1% of patients [1.2.3]. The critical question, Can nitrofurantoin cause blisters?, is important because blistering can signify a rare but life-threatening condition requiring immediate medical attention [1.3.1, 1.2.1].

Quick Summary

Nitrofurantoin, an antibiotic for UTIs, can rarely cause blisters as part of a severe cutaneous adverse reaction (SCAR) [1.2.3, 1.3.1]. This overview details the potential risks, symptoms to watch for, and necessary actions if they occur.

Key Points

Blisters are a rare but serious side effect: While most side effects are mild, developing blisters while on nitrofurantoin can indicate a severe reaction like Stevens-Johnson syndrome [1.2.3, 1.3.1].
Severe Reactions are a Medical Emergency: Conditions like SJS and TEN are characterized by blistering, peeling skin and require immediate hospital care [1.3.6, 1.5.1].
Know the Early Symptoms: Flu-like symptoms (fever, sore throat) followed by a painful, spreading rash and blisters are classic signs of a severe cutaneous adverse reaction (SCAR) [1.2.7].
Stop the Medication Immediately: If you suspect a severe reaction, stop taking nitrofurantoin and contact your doctor or seek emergency care right away [1.6.2].
Common Side Effects Differ Greatly: Nausea, headaches, and harmless brown urine are common and not dangerous, unlike widespread blistering, which is a medical emergency [1.2.3, 1.2.7].
Inform All Healthcare Providers: Always disclose any drug allergies or past adverse reactions to your doctors and pharmacists to prevent future issues.
Alternatives Are Available: If an allergic reaction occurs, alternative antibiotics like fosfomycin or trimethoprim-sulfamethoxazole can be used to treat the UTI [1.8.3, 1.8.5].

What is Nitrofurantoin and How Does It Work?

Nitrofurantoin is an antibiotic medication primarily used to treat and prevent urinary tract infections (UTIs) caused by bacteria [1.6.4, 1.8.3]. Available under brand names like Macrobid and Macrodantin, it functions by inhibiting bacterial DNA, RNA, and protein synthesis within the urinary tract [1.6.4]. One of its key advantages is that there is minimal bacterial resistance to it, making it a good first-line option for uncomplicated UTIs [1.8.3]. A common, harmless side effect is the darkening of urine to a brown color [1.2.7]. Patients are typically advised to take nitrofurantoin with food to improve absorption and minimize stomach upset [1.6.4, 1.7.5].

The Link Between Nitrofurantoin and Skin Reactions

While effective, nitrofurantoin can cause various side effects, including skin reactions [1.2.3]. Cutaneous (skin) reactions are among the most common adverse effects, though most are mild [1.4.1]. These can manifest as a simple skin rash, itching, or hives (urticaria) [1.2.2, 1.2.1]. In clinical studies, such allergic reactions were observed in less than 1% to 4.1% of patients, depending on the study [1.2.3, 1.4.2]. Most mild rashes resolve after discontinuing the medication [1.4.1].

Can Nitrofurantoin Cause Blisters? The Direct Answer

Yes, though rarely, nitrofurantoin can cause blisters [1.2.2, 1.2.4]. Blistering is not a common side effect but a sign of a severe, and potentially life-threatening, allergic reaction [1.2.1]. The appearance of a painful, reddish-purple skin rash accompanied by blistering and peeling skin requires immediate medical attention [1.2.3, 1.6.5]. These symptoms may indicate a severe cutaneous adverse reaction (SCAR), such as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) [1.3.1, 1.3.2].

Understanding Severe Cutaneous Adverse Reactions (SCARs)

SCARs are a group of dangerous drug reactions affecting the skin and mucous membranes. Nitrofurantoin has been identified as a potential trigger for these conditions [1.3.1, 1.3.5].

Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN): These are the most severe forms of SCARs. They are characterized by widespread blistering and peeling of the skin, resembling a severe burn [1.3.2, 1.3.6]. SJS involves less than 10% of the body's skin surface, while TEN involves more than 30% [1.3.3]. The mortality rate for these conditions can be high, making early recognition crucial [1.3.6, 1.3.7].
DRESS Syndrome: Another rare but serious reaction linked to nitrofurantoin is Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). It involves a rash, fever, and inflammation of internal organs [1.3.5].
Exfoliative Dermatitis: This is a severe inflammation of the entire skin surface, causing redness, scaling, and peeling [1.7.5, 1.4.7].

Symptoms of SJS/TEN often begin with flu-like signs such as fever, sore throat, and burning eyes, followed by the rapid development of a painful rash that spreads and blisters [1.2.7].

Common vs. Serious Side Effects of Nitrofurantoin

It is vital to distinguish between common, manageable side effects and the signs of a serious reaction. Taking nitrofurantoin with food or milk can help minimize common gastrointestinal issues [1.7.5].


Side Effect Category	Examples	Action Required	Source(s)
Common	Nausea, vomiting, headache, loss of appetite, gas, brown-colored urine.	Usually do not require medical attention unless persistent or bothersome.	[1.2.3, 1.7.2, 1.7.5]
Less Common	Diarrhea, dizziness, mild skin rash, itching.	Report to your care team if they continue or are bothersome.	[1.7.2, 1.7.4]
Rare & Serious	Blistering, peeling skin, severe rash, difficulty breathing, chest pain, persistent cough, yellowing of skin/eyes (jaundice), severe stomach pain, numbness or tingling in hands/feet, severe diarrhea (even months after stopping).	Seek immediate medical attention or go to A&E.	[1.2.1, 1.2.2, 1.2.3, 1.6.1]

What to Do If You Develop Blisters

If you develop a rash with blisters, peeling skin, or sores in your mouth while taking nitrofurantoin, you must take immediate action [1.2.2, 1.6.1].

Stop taking nitrofurantoin immediately. Continuing the medication can worsen the reaction [1.6.2].
Contact your doctor or seek emergency medical care right away. Call 911 or go to the nearest emergency room [1.6.3].
Do not attempt to treat severe blisters at home. These conditions require hospitalization, often in a specialized burn unit, for wound care, fluid management, and to prevent infection [1.5.1].
Inform all healthcare providers about your reaction. This adverse event should be permanently recorded in your medical history.

Managing UTI Treatment Safely

If you have an allergic reaction to nitrofurantoin, your doctor will prescribe an alternative antibiotic. Common alternatives for treating UTIs include trimethoprim-sulfamethoxazole (Bactrim), fosfomycin (Monurol), and cephalexin [1.8.2, 1.8.3, 1.8.5]. The choice of antibiotic depends on local resistance patterns and individual patient factors [1.8.5].

Conclusion

To answer the question, can nitrofurantoin cause blisters?, the answer is unequivocally yes, but it is a rare and serious event [1.2.2, 1.2.3, 1.3.1]. While most side effects of nitrofurantoin are mild and gastrointestinal in nature, the development of blisters is a red flag for a life-threatening medical emergency like SJS/TEN [1.3.2]. Patients should be aware of both common side effects and the urgent signs of a severe reaction. Immediate discontinuation of the drug and prompt medical evaluation are essential for managing these severe reactions and ensuring patient safety.

For more information from a trusted medical source, you can visit: https://www.nhs.uk/medicines/nitrofurantoin/side-effects-of-nitrofurantoin/

Frequently Asked Questions

A mild skin rash or itching can occur as a side effect of nitrofurantoin [1.2.2]. However, you should report any rash to your doctor. If the rash is accompanied by blistering, peeling, fever, or sores, seek emergency medical care immediately [1.2.3, 1.6.1].

Blisters from a severe reaction to nitrofurantoin are often part of a painful, red or purple skin rash that spreads [1.2.3, 1.2.7]. The skin may then blister and peel, and you might also develop sores on mucous membranes like the mouth and eyes [1.2.2, 1.2.4].

A severe reaction can occur within hours if you've taken the drug before, or within days to weeks of starting it for the first time [1.7.5]. Symptoms often start with a fever and sore throat before the rash appears [1.2.7].

No. Blistering reactions like SJS/TEN are medical emergencies that cannot be treated at home. They require immediate hospitalization for specialized care, often in a burn unit, to manage the skin, provide fluids, and prevent infection [1.5.1].

Other serious side effects include lung problems (persistent cough, chest pain, difficulty breathing), liver problems (yellow skin/eyes, dark urine), nerve problems (numbness, tingling, or pain in hands/feet), and signs of blood problems (unexplained bruising, fever, sore throat) [1.6.1, 1.2.2, 1.2.3].

Yes, Macrobid is a brand name for a long-acting version of nitrofurantoin [1.7.5]. The potential side effects, including the rare risk of severe blistering reactions, apply to both the generic and brand-name versions.

For a mild rash, call your doctor right away for advice [1.6.3]. For a severe reaction involving blistering, peeling skin, swelling of the face/throat, or trouble breathing, stop the medication and call 911 or go to the nearest emergency department immediately [1.6.1, 1.6.3].