Table of ContentsView AllTable of ContentsOverviewSulfa Drug ListAllergy RiskSymptomsSide EffectsTreatment and Prevention

Table of ContentsView All

View All

Table of Contents

Overview

Sulfa Drug List

Allergy Risk

Symptoms

Side Effects

Treatment and Prevention

Sulfa drugs are synthetic (man-made) medications made fromsulfanilamidethat contain antibacterial properties. Sulfa drugs were the first class of antibiotics ever discovered.However, many other medications may contain sulfa too, such as medications for diabetes, thyroiditis, and arthritis.

Some people have a sulfa allergy and need to avoid medications containing sulfonamides.

This article lists specific sulfa drugs and symptoms of an allergic reaction that could occur if you are sensitive to sulfa.

What Drugs to Avoid If You Have a Sulfa Allergy

What Are Sulfanilamides?

Sulfanilamides, also calledsulfonamides, are made through chemical reactions. They are an important class of antibiotics and are also used to treat a variety of health conditions, including:

Medications containing sulfonamide include:

Sulfonamide-containing nonantimicrobial agents include several classes of drugs. Some healthcare providers will avoid prescribing these to people with an allergy to sulfonamide-containing antimicrobials. However, research has shown that a reaction is unlikely, so they might be prescribed.These drugs include.

Antibiotics Without SulfaThere are many non-sulfa antibiotics that you can take in place of sulfa-containing antimicrobials. Two classes of antibiotics that don’t contain sulfa are penicillins (like amoxicillin) and fluoroquinolones (like Cipro).The specific antibiotic that will work best for you will depend on the bacteria in question and your allergy profile.

Antibiotics Without Sulfa

There are many non-sulfa antibiotics that you can take in place of sulfa-containing antimicrobials. Two classes of antibiotics that don’t contain sulfa are penicillins (like amoxicillin) and fluoroquinolones (like Cipro).The specific antibiotic that will work best for you will depend on the bacteria in question and your allergy profile.

There are many non-sulfa antibiotics that you can take in place of sulfa-containing antimicrobials. Two classes of antibiotics that don’t contain sulfa are penicillins (like amoxicillin) and fluoroquinolones (like Cipro).

The specific antibiotic that will work best for you will depend on the bacteria in question and your allergy profile.

Risk of Allergic Reaction to Sulfa Drugs

Asulfa allergyis an allergy to drugs with a sulfonamide group as part of their chemical structure. These can be antibiotics, diuretics (water pills), eye drops, topical creams, and other types of drugs.

Sulfa-based antibiotics are commonly used to treat skin, hospital-acquired, and fungal infections. Some researchers estimate that sulfa allergies impact up to 8% of people who use these drugs worldwide.

In some people, sulfa drugs can cause the body to releasehistamine, causing a systemic (body-wide) inflammatory response that can affect one or more organs.

If you have a sulfa allergy, you should avoid antibiotics such as Bactrim or Septra (TMP/SMX, trimethoprim-sulfamethoxazole). Trimethoprim-sulfamethoxazole is the most commonly used sulfa antibiotic. Because sulfamethoxazole is often combined with trimethoprim, any antibiotic with trimethoprim should be avoided.

People with HIV are at increased risk for experiencing allergic reactions to sulfonamide antimicrobials. Sulfonamide allergic reactions affect 3% to 8% of the general population but are 10 to 20 times more likely in people with HIV.

Sulfa Allergy vs. Sulfite AllergySulfa is mostly contained in medications and supplements, whereas sulfites are added as a preservative to many processed foods and occur naturally in fermented foods, including beer and wine.The symptoms of a sulfite allergy are asthma-like (runny nose, sneezing, watery eyes, and wheezing) as compared to a rash with a sulfa allergy. These are two separate types of allergies with no connection between them.

Sulfa Allergy vs. Sulfite Allergy

Sulfa is mostly contained in medications and supplements, whereas sulfites are added as a preservative to many processed foods and occur naturally in fermented foods, including beer and wine.The symptoms of a sulfite allergy are asthma-like (runny nose, sneezing, watery eyes, and wheezing) as compared to a rash with a sulfa allergy. These are two separate types of allergies with no connection between them.

Sulfa is mostly contained in medications and supplements, whereas sulfites are added as a preservative to many processed foods and occur naturally in fermented foods, including beer and wine.

The symptoms of a sulfite allergy are asthma-like (runny nose, sneezing, watery eyes, and wheezing) as compared to a rash with a sulfa allergy. These are two separate types of allergies with no connection between them.

Symptoms of Sulfa Allergy

Sulfa allergies can present in a multitude of ways, including as a rash. Your reaction may range from mild to severe.

No matter how your allergies present, you should consult a healthcare provider immediately. An initially mild allergic reaction can quickly progress toanaphylaxis, a severe life-threatening reaction requiring emergency medical care.

A generalized flat, red rash, also known asmaculopapulareruption, is the most common symptom of a sulfa allergy, but you may also experience the following symptoms:

Sun exposure can trigger or worsen your rash. Finding some shade and cooling your body down with ice are some initial steps you can take should you develop a mild skin rash.

Other Side Effects of Sulfa Drugs

Sulfa drugs may also cause other side effects besides an allergic reaction, such as:

Rare severe side effects include:

Treatment and Prevention of Allergies and Sensitivity

There is no test for a sulfa allergy, so people usually find out that they have an allergy after an adverse medical reaction to a drug, supplement, or personal care product. The diagnosis is made based on your symptoms, physical examination, and medical history.

A sulfa reaction usually resolves within two weeks of stopping the offending medication. Discontinuation soon after the appearance of an itchy rash or hives may lead to a resolution of your symptoms. Antihistamines and corticosteroids may also be prescribed to relieve symptoms.

Some healthcare providers may try a desensitization program for an allergy to sulfa drugs, prescribing small but increasing doses to improve tolerance.

You may be able to take some medications with sulfa that are low-risk. However, be sure to report any known or suspected allergies to a healthcare provider so they can prescribe other types of medications to avoid triggering a reaction.

Summary

Sulfa allergies are usually experienced early after taking medications and typically present as a rash. Once the offending medication is stopped, symptoms usually resolve within two weeks. Antihistamines and corticosteroids can help relieve symptoms in the meantime.

See a healthcare provider if you have a reaction and seek emergency medical care for a severe reaction. Always inform a healthcare provider of a known sulfa allergy to prevent future allergic reactions.

13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health.How sulfa drugs work.Ovung A, Bhattacharyya J.Sulfonamide drugs: structure, antibacterial property, toxicity, and biophysical interactions. Biophys Rev. 2021 Mar 29;13(2):259-272. doi: 10.1007/s12551-021-00795-9Merck Manual Professional Version.Sulfonamides.American College of Rheumatology.Sulfasalazine (Azulfidine).MedlinePlus.Co-trimoxazole.MedlinePlus.Erythromycin and sulfisoxazole.MedlinePlus.Silver Sulfadiazine.American Diabetes Association.What are my options for type 2 diabetes medications?Giles A, Foushee J, Lantz E, Gumina G.Sulfonamide allergies.Pharmacy (Basel). 2019;7(3):132. doi:10.3390/pharmacy7030132LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-.Sulfonamides. [Updated 2017 Dec 5]American College of Allergy, Asthma, and Immunology.Drug allergies.Penn Medicine.Drug allergy.Mechtler AG, Chamarro-Pareja N, Carillo-Martin I, Haehn D, Gonzalez-Estrada A.Six-step trimethoprim-sulfamethoxazole desensitization protocol in non-HIV patients with self-reported sulfa allergy: a single center experience.J Allergy Clin Immunol.2019:143(2):AB33. doi:10.1016/j.jaci.2018.12.102

13 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health.How sulfa drugs work.Ovung A, Bhattacharyya J.Sulfonamide drugs: structure, antibacterial property, toxicity, and biophysical interactions. Biophys Rev. 2021 Mar 29;13(2):259-272. doi: 10.1007/s12551-021-00795-9Merck Manual Professional Version.Sulfonamides.American College of Rheumatology.Sulfasalazine (Azulfidine).MedlinePlus.Co-trimoxazole.MedlinePlus.Erythromycin and sulfisoxazole.MedlinePlus.Silver Sulfadiazine.American Diabetes Association.What are my options for type 2 diabetes medications?Giles A, Foushee J, Lantz E, Gumina G.Sulfonamide allergies.Pharmacy (Basel). 2019;7(3):132. doi:10.3390/pharmacy7030132LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-.Sulfonamides. [Updated 2017 Dec 5]American College of Allergy, Asthma, and Immunology.Drug allergies.Penn Medicine.Drug allergy.Mechtler AG, Chamarro-Pareja N, Carillo-Martin I, Haehn D, Gonzalez-Estrada A.Six-step trimethoprim-sulfamethoxazole desensitization protocol in non-HIV patients with self-reported sulfa allergy: a single center experience.J Allergy Clin Immunol.2019:143(2):AB33. doi:10.1016/j.jaci.2018.12.102

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Institutes of Health.How sulfa drugs work.Ovung A, Bhattacharyya J.Sulfonamide drugs: structure, antibacterial property, toxicity, and biophysical interactions. Biophys Rev. 2021 Mar 29;13(2):259-272. doi: 10.1007/s12551-021-00795-9Merck Manual Professional Version.Sulfonamides.American College of Rheumatology.Sulfasalazine (Azulfidine).MedlinePlus.Co-trimoxazole.MedlinePlus.Erythromycin and sulfisoxazole.MedlinePlus.Silver Sulfadiazine.American Diabetes Association.What are my options for type 2 diabetes medications?Giles A, Foushee J, Lantz E, Gumina G.Sulfonamide allergies.Pharmacy (Basel). 2019;7(3):132. doi:10.3390/pharmacy7030132LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-.Sulfonamides. [Updated 2017 Dec 5]American College of Allergy, Asthma, and Immunology.Drug allergies.Penn Medicine.Drug allergy.Mechtler AG, Chamarro-Pareja N, Carillo-Martin I, Haehn D, Gonzalez-Estrada A.Six-step trimethoprim-sulfamethoxazole desensitization protocol in non-HIV patients with self-reported sulfa allergy: a single center experience.J Allergy Clin Immunol.2019:143(2):AB33. doi:10.1016/j.jaci.2018.12.102

National Institutes of Health.How sulfa drugs work.

Ovung A, Bhattacharyya J.Sulfonamide drugs: structure, antibacterial property, toxicity, and biophysical interactions. Biophys Rev. 2021 Mar 29;13(2):259-272. doi: 10.1007/s12551-021-00795-9

Merck Manual Professional Version.Sulfonamides.

American College of Rheumatology.Sulfasalazine (Azulfidine).

MedlinePlus.Co-trimoxazole.

MedlinePlus.Erythromycin and sulfisoxazole.

MedlinePlus.Silver Sulfadiazine.

American Diabetes Association.What are my options for type 2 diabetes medications?

Giles A, Foushee J, Lantz E, Gumina G.Sulfonamide allergies.Pharmacy (Basel). 2019;7(3):132. doi:10.3390/pharmacy7030132

LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-.Sulfonamides. [Updated 2017 Dec 5]

American College of Allergy, Asthma, and Immunology.Drug allergies.

Penn Medicine.Drug allergy.

Mechtler AG, Chamarro-Pareja N, Carillo-Martin I, Haehn D, Gonzalez-Estrada A.Six-step trimethoprim-sulfamethoxazole desensitization protocol in non-HIV patients with self-reported sulfa allergy: a single center experience.J Allergy Clin Immunol.2019:143(2):AB33. doi:10.1016/j.jaci.2018.12.102

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