LoryAnn asked
I'm trying to find out what to treat the rash I got that I believe is from being on Macrobid? I forgot I was on it and laid in the sun. Now I have a rash on my legs and arms but not on my tummy or back? I wore a bikini.
At a glance
- Macrobid (nitrofurantoin) is an antibiotic medication used in the treatment of urinary tract infections.
- Nitrofurantoin is not usually associated with sensitivity to sunlight (photosensitivity) but they have been reported.
- Severe dermatologic or allergic reactions caused by nitrofurantoin are rare, occurring in <1% of patients.
- You should let your doctor or healthcare provider know that this reaction occurred as it may be a sign of an allergic reaction to nitrofurantoin, and he/she may need to examine the rash to determine the best course of action.
Answer
Macrobid (Nitrofurantoin) is an antibiotic medication that is specifically used for the treatment of urinary tract infections. It works by concentrating in the urinary tract where it disrupts bacterial cellular processes.
While photosensitivity reactions are listed as a side effect (and you may see a warning sticker on your prescription vial), they are relatively uncommon, especially when compared to other classes of antibiotics, like 'tetracyclines'. Nevertheless, they certainly do occur and some people may be more susceptible than others.
Generally, if they do occur, these reactions happen quickly and manifest as an exaggerated sunburn. A common counseling point by pharmacists on this drug is that you 'may burn more easily', which is certainly true for many.
More severe dermatologic reactions, such as rash, are rare, however, occurring in <1% of patients.
These more severe reactions are often referred to as hypersensitivity or allergic reactions. They can result in the following:
• Maculopapular rash (usually presenting as flat or raised red spots)
• Erythematous rash (usually presenting as redness of the skin)
• Eczematous rash (usually presenting as red itchy lesions)
• Hives and itching
As what you are describing could be a sign of an allergic reaction to nitrofurantoin, I think it is best to let your doctor or healthcare provider know about the rash and have them determine the best course of action, just to be on the safe side. It wouldn't be the best course of action to self-treat without an evaluation from your doctor in a situation like this.
As a general rule of thumb, the best way to manage drugs that can cause photosensitivity reactions is prevention.
However, if a reaction has already occurred, topical products like aloe vera can help the skin heal and reduce inflammation. For more serious reactions, corticosteroids are sometimes prescribed. As mentioned above, it would be prudent to discuss reactions that look more severe than a sunburn with your doctor.
References
Macrobid [package insert]. Norwich, NY: Norwich Pharmaceuticals, Inc.; 2009.
Drug-induced Photosensitivity. PubMed
Management of uncomplicated urinary tract infections. PubMed
