What medications have sulfonamides in them? Your guide to sulfa drugs

October 12, 2025 •

2 min read

According to studies, hypersensitivity reactions to sulfonamide antibiotics occur in roughly 4% to 6% of the general population. This makes understanding what medications have sulfonamides in them crucial, especially for individuals with a known sulfa allergy or history of adverse reactions.

Quick Summary

Beyond antibiotics, many other medication classes, including diuretics, diabetes drugs, and anti-inflammatories, contain sulfonamide components. Navigating a sulfa allergy involves identifying both antibiotic and non-antibiotic sulfonamides and understanding the varying risks of cross-reactivity between them.

Key Points

Broad Medication Class: Sulfonamides include antibiotics and non-antibiotics, affecting various drug classes like diuretics, diabetes medications, and NSAIDs.
Antibiotic vs. Non-Antibiotic Sulfonamides: The distinction is critical, as antibiotic sulfonamides (e.g., Bactrim) are the primary cause of sulfa allergies.
Low Cross-Reactivity Risk: Allergic reactions to sulfonamide antibiotics have a very low risk of predicting a reaction to non-antibiotic sulfonamides like hydrochlorothiazide or celecoxib.
Sulfites Are Different: A sulfa drug allergy is not related to an allergy to sulfites, which are food preservatives.
Patient Awareness Is Key: Always inform your healthcare provider of a sulfa antibiotic allergy to ensure proper medication selection and prevent potential adverse reactions.
Severe Reaction Signs: Be aware of serious allergic reaction signs, which can include anaphylaxis, Stevens-Johnson syndrome, and Toxic Epidermal Necrolysis.

Sulfonamides, also known as sulfa drugs, are a group of medications sharing a specific chemical structure. Initially used as antibiotics, they are now found in various drug classes treating conditions like infections, hypertension, and diabetes. While cross-reactivity is a concern among sulfonamide antibiotics, it is very low between antibiotic and non-antibiotic sulfonamides.

Sulfonamide Antibiotics: The Classic 'Sulfa Drugs'

These are commonly associated with sulfa allergies and treat bacterial infections by inhibiting folic acid synthesis.

Examples of Sulfonamide Antibiotics

Oral: Sulfamethoxazole/trimethoprim (Bactrim, Septra), Erythromycin/sulfisoxazole, Sulfadiazine, Sulfisoxazole.
Topical: Silver sulfadiazine (Silvadene), Sulfacetamide (Klaron), Mafenide (Sulfamylon).

Non-Antibiotic Medications with Sulfonamides

Many drugs contain a sulfonamide structure for non-antibiotic purposes, with a low risk of cross-allergic reaction with sulfonamide antibiotics.

Examples of Non-Antibiotic Sulfonamides

Diuretics: Hydrochlorothiazide (Microzide), Chlorthalidone, Furosemide (Lasix), Bumetanide (Bumex).
Diabetes Medications (Sulfonylureas): Glipizide (Glucotrol), Glyburide (Glynase), Glimepiride (Amaryl).
Other Classes: Celecoxib (Celebrex), Acetazolamide (Diamox), Dorzolamide (Trusopt), Certain HIV Protease Inhibitors (darunavir, fosamprenavir), Sulfasalazine (Azulfidine), Sumatriptan (Imitrex), Probenecid, Tamsulosin (Flomax).

A Comparison of Sulfonamide Medication Types

Understanding the differences between antibiotic and non-antibiotic sulfonamides is key for managing allergies.


Feature	Sulfonamide Antibiotics	Non-Antibiotic Sulfonamides
Common Examples	Trimethoprim/Sulfamethoxazole (Bactrim), Silver Sulfadiazine, Sulfasalazine*	Hydrochlorothiazide (HCTZ), Furosemide (Lasix), Glipizide (Glucotrol), Celecoxib (Celebrex), Sumatriptan (Imitrex)
Primary Purpose	Treat or prevent bacterial infections	Treat conditions like hypertension, diabetes, glaucoma, and inflammation
Chemical Structure	Contain an arylamine group at the N4 position	Lack the arylamine group and have a different structure
Cross-Reactivity Risk	High among different sulfonamide antibiotics	Very Low with antibiotic sulfonamides
Allergy Prevalence	Higher prevalence, especially in patients with HIV	Standard risk, not linked to a sulfa antibiotic allergy
Primary Allergy Concern	The risk is mainly from the specific antibiotic component	Allergic reactions are typically unrelated to a sulfa antibiotic allergy

*Note: Sulfasalazine contains a sulfonamide antibiotic component, so cross-reactivity is a risk for those allergic to sulfamethoxazole.

Sulfonamide Allergy and Its Implications

A true sulfa allergy is a reaction to drugs with the sulfonamide group, most often antibiotics. It is distinct from a sulfite allergy. Symptoms range from mild (rash, hives, photosensitivity) to severe (anaphylaxis, SJS/TEN).

Cross-Reactivity

Cross-reactivity is likely between different sulfonamide antibiotics due to similar structures. However, the risk is very low for non-antibiotic sulfonamides as they lack the specific structure that triggers most antibiotic sulfa allergies. Individuals with a sulfa antibiotic allergy can often safely use drugs like furosemide or celecoxib.

Conclusion

Identifying medications with sulfonamides requires distinguishing between antibiotic and non-antibiotic types. Sulfonamide antibiotics are the main cause of sulfa allergies, with cross-reactivity a concern within this group. Non-antibiotic sulfonamides, however, carry a very low risk of cross-reaction for those with a sulfa antibiotic allergy. Always inform healthcare providers about any drug allergies to ensure safe medication choices.

For additional details on sulfa allergies and medication safety, resources like the Cleveland Clinic offer valuable information.

Frequently Asked Questions

Yes, Bactrim is a combination antibiotic that contains sulfamethoxazole, a common sulfonamide antibiotic. It is frequently associated with allergic reactions in those sensitive to sulfa drugs.

The risk of an allergic reaction to non-antibiotic sulfonamides like hydrochlorothiazide (a diuretic) in a person with a sulfa antibiotic allergy is very low. Most evidence suggests no significant cross-reactivity.

A sulfa allergy is a reaction to sulfonamide drugs, while a sulfite allergy is a reaction to sulfite preservatives found in some foods and wines. These two types of allergies are chemically unrelated.

Common symptoms include skin rash, hives, and photosensitivity. Severe, but less common, reactions can include anaphylaxis or severe skin conditions like Stevens-Johnson syndrome.

Yes, Celebrex (celecoxib) is a non-antibiotic sulfonamide (a COX-2 inhibitor). The risk of cross-reactivity with a sulfa antibiotic allergy is considered very low.

Yes, hypersensitivity reactions to sulfonamide antibiotics are reported to be 10 to 20 times more likely in patients with HIV compared to the general population.

No. Sulfate is a different chemical compound from the sulfonamide group. Medications like morphine sulfate or ferrous sulfate are safe for people with a sulfa allergy.