What drugs should be avoided with a sulfa allergy?

Medically reviewed by Sally Chao, MD. Last updated on Oct 31, 2024.

Official Answer by Drugs.com

People with a sulfa allergy typically need to avoid sulfonamide antibiotics (antibiotics containing sulfa), including:

Septra and Bactrim (sulfamethoxazole-trimethoprim)
Pediazole (erythromycin-sulfisoxazole)

Whether other nonantibiotic sulfa-containing drugs need to be avoided with sulfa allergy is unclear and considered on a case-by-case basis.

Sulfa can be found in many different drugs, but sulfonamide antibiotics cause the majority of sulfa allergies. Research is mixed on whether there is an association between allergies to antibiotic sulfa drugs and nonantibiotic sulfa drugs. Experiencing an allergic reaction to a sulfonamide antibiotic does not mean that you will react poorly to sulfonamide nonantibiotic drugs.

While the risk is low, people with an allergy to sulfa antibiotics may have a higher risk of reacting poorly to nonantibiotic sulfa drugs. It may be that sulfa antibiotic allergies are associated with a greater risk of drug allergies overall. One study reported in a review in Canadian Family Physician found that penicillin, which is substantially different from sulfa antibiotics, was more likely to cause an allergic reaction than sulfa nonantibiotics among people allergic to sulfa antibiotics.

Besides antibiotics, some of the drugs that contain sulfa include:

Antivirals, such as amprenavir and fosamprenavir
Carbonic anhydrase inhibitors, such as acetazolamide and brinzolamide
COX-2 inhibitors, such as celecoxib and rofecoxib
Loop diuretics, such as bumetanide and furosemide
Sulfonylureas, such as acetohexamide and chlorpropamide
Thiazide diuretics, such as benzthiazide and chlorothiazide
Triptans, such as almotriptan and eletriptan

It is important for your doctor to be aware of your history of drug allergies so that you and your doctor can make careful decisions and weigh the risks and benefits in each case.

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Yes, Bactrim (sulfamethoxazole and trimethoprim) can make you tired. Fatigue, or feeling tired, is a side effect listed in the Bactrim prescribing information. Some people reported feeling tired while taking it during clinical trials. Continue reading

Can you take hydroxyzine for anxiety and sleep?

Hydroxyzine is a sedating antihistamine that can be used short-term to treat anxiety and trouble sleeping, but is not meant for long-term use. Medicines typically used first-line for the treatment of anxiety are the antidepressants like the SSRIs or SNRIs (for example: paroxetine, sertraline, escitalopram). Continue reading

Amoxicillin rash: When should I be concerned?

From 5% to 10% of children will develop a rash from amoxicillin after taking it, which in most cases, is considered a side effect of amoxicillin and not an allergic rash. But in a small number of cases, the rash will be a sign of an allergic reaction which means the amoxicillin will need to be stopped right away. Continue reading

What drugs should be avoided with a sulfa allergy?

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