Allergies Drug & Latex Allergies An Overview of Sulfa Allergy By Daniel More, MD Daniel More, MD, is a board-certified allergist and clinical immunologist with a background in internal medicine. Learn about our editorial process Daniel More, MD Medically reviewed by Medically reviewed by Corinne Savides Happel, MD on February 14, 2020 linkedin Corinne Savides Happel, MD, is a board-certified allergist and immunologist with a focus on allergic skin disorders, asthma, and other immune disorders. Learn about our Medical Review Board Corinne Savides Happel, MD Updated on February 14, 2020 Print Table of Contents View All Table of Contents Symptoms Causes Diagnosis Treatment Prevention Sulfa allergy is a term used to describe an adverse drug reaction to sulfonamides, a class of drugs that includes both antibiotics and non-antibiotics. Such a response to sulfa is not all that uncommon. Whether caused by a true allergy or drug intolerance, sulfa reactions affect up to 6% of all people (women more than men). The rate is similar to what is seen with reactions to other types of antibiotics, including penicillin. Illustration by Brianna Gilmartin, Verywell Two of the more common sulfa drugs associated with sulfa allergy are: Sulfamethoxazole-trimethoprim (marketed under the brand names Bactrim, Septra, and others) Erythromycin-sulfafurazole (marketed under the brand names Eryzole, Pediazole, and others) Guidelines for Prescribing Antibiotics Symptoms The symptoms and severity of a sulfa allergy can vary from mild to life-threatening. Call your doctor if you develop symptoms of a sulfa allergy, however mild, and seek emergency care if symptoms are severe and rapidly progressing. In some cases, continuing a sulfa drug while having mild symptoms may cause those mild symptoms to become severe and life-threatening. Common Common symptoms of sulfa allergy are often limited to the skin and may include: Pruritus (itchy skin) Urticaria (hives) Generalized maculopapular rash (a widespread rash with flat and raised lesions) Angioedema (swelling of the face, hands, and other tissues) Photosensitive rash (one that occurs in areas of ultraviolet light exposure) Severe Certain people may develop more severe or even life-threatening symptoms that require emergency medical attention. Chief among these is anaphylaxis, a potentially life-threatening, whole-body allergy that can lead to shock, coma, respiratory or heart failure, and death if left untreated. When to Call 911 Seek emergency care if you experience the following signs of anaphylaxis: Swelling of the throat or tongue Difficulty swallowing Difficulty breathing or rapid breathing Wheezing Lightheadedness or fainting Racing heart or irregular heartbeat Nausea or vomiting Severe rash or hives Blue-colored skin A feeling of impending doom Anaphylaxis tends to occur within minutes to several hours of a dose. Other reactions take longer to develop. This includes reactions know as Stevens-Johnson syndrome and toxic epidermal necrolysis in which large areas of skin will blister and delaminate, posing the risk of severe dehydration, shock, and death if left untreated. As opposed to anaphylaxis, SJS and TEN typically develop within 8 weeks of exposure to a drug (usually between 4 and 30 days). This photo contains content that some people may find graphic or disturbing. See Photo Stevens-Johnson syndrome on the face. DermNet / CC BY-NC-ND Causes Certain people appear to be at higher risk of sulfa allergy than others. These include people who are severely immunocompromised, including organ transplant recipients and people with advanced HIV infection. There's a common misconception that all sulfonamide drugs are equally likely to cause an allergic or adverse reaction. While all sulfa drugs have the potential for this, research suggests that antibiotic sulfonamides (used to treat bacterial infections) are more likely to trigger an allergic reaction than non-antibiotic ones. Diagnosis There are no skin or blood tests available to diagnose a sulfa allergy. The diagnosis is usually based on a careful examination of symptoms as well as a review of your current and previous medication use. Ideally, a physician will document what specific sulfa drug was associated with what specific reaction. This ensures that the drug is avoided in the future even if it is sold under a different trade name. Once the drug that caused the reaction is determined, it's a good idea to keep a record of it (and even wear a medical bracelet advising of the concern) in the event of a future incident. Treatment The first-line treatment of a sulfa allergy is the termination of the suspected drug. However, in milder cases where a sulfa drug is considered essential to the treatment of an infection, your doctor and/or allergist may supervise the administration of smaller doses, gradually increasing the dose as tolerated. This is referred to as allergy desensitization. Anaphylaxis requires an immediate epinephrine injection to halt the reaction, followed by supportive care and non-inflammatory medications such as corticosteroids. SJS and TEN also require emergency medical treatment, including pain medications, corticosteroids, and intravenous hydration. Severe cases often require the care of a burn center. This photo contains content that some people may find graphic or disturbing. See Photo Stevens-Johnson syndrome on backside. DermNet / CC BY-NC-ND Prevention People with a known sulfa allergy should always check with their doctor before starting a new medication. This is especially true for those who have had a previous severe reaction to sulfa drugs. For many with a sulfa allergy, there typically is a low risk of reacting to non-antibiotic sulfonamides. However, topical sulfa antibiotic medications should be avoided if you are known to be hypersensitive. These include: Sulfacetamide shampoos, creams, and eye drops Silver sulfadiazine ointments used to treat burns Sulfanilamide vaginal preparations Similarly, the oral drug Azulfidine (sulfasalazine) used to treat Crohn's disease, ulcerative colitis, and rheumatoid arthritis should be avoided. Since the risk of cross-reactivity to non-antibiotic sulfonamides is low, it is considered generally safe to take the following drugs: Celebrex (celecoxib), a COX-2 inhibitor used to treat arthritis Diamox (acetazolamide) used to treat epilepsy, intracranial hypertension, glaucoma, and heart failure Diuretics like Bumex (bumetanide), HCTZ (hydrochlorothiazide), Lasix (furosemide), and Thalitone (chlorthalidone), Migraine medications like Frova (frovatriptan), Imitrex (sumatriptan), and Relpax (eletriptan) Non-antibiotic eye drops like Genoptic (gentamicin sulfate), Isopto Atropine (atropine sulfate), Maxitrol (neomycin + dexamethasone + polymyxin B), and Polytrim (polymyxin B + trimethoprim) Oral sulfonylureas-class drugs like Amaryl (glimepiride), Glynase (glyburide), and (Glucotrol) glipizide used to treat type 2 diabetes Sulfonamides vs. Sulfates Sulfates are compounds containing sulfuric acid that are used as preservatives in packaged foods and wine. They can cause reactions in some people but are not related in any way to sulfonamides. As such, you don't need to avoid sulfates if you have a sulfa allergy. Understanding Sulfite Allergy A Word From Verywell The nuances of a sulfa allergy can be tricky to tease out, even for some healthcare providers. That's why it's important to tell your doctor about any prior reaction you may have had to a sulfa medication (or any other drug for that matter). Sharing that information will make it easier for your doctor to prescribe a substitute that is less likely to cause an adverse reaction. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Giles A, Foushee J, Lantz E, Gumina G. Sulfonamide allergies. Pharmacy (Basel). 2019 Sep;7(3):132. doi:10.3390/pharmacy7030132 Wulf, N. and Matuszewski, K. Sulfonamide cross-reactivity: is there evidence to support broad cross-allergenicity? Am J Health Syst Pharm. 2013 Sep 1;70(17):1483-94. doi:10.2146/ajhp120291 Patterson RA, Stankewicz HA. Penicillin allergy. In: StatPearls [Internet]. Updated August 14, 2020. Schnyder B, Pichler WJ. Allergy to sulfonamides. J Allergy Clin Immunol. 2013;131(1):256-7.e1-5. doi:10.1016/j.jaci.2012.10.003 American Academy of Allergy, Asthma & Immunology. Anaphylaxis. Updated 2021. Mali S, Jambure R. Anaphylaxis management: current concepts. Anesth Essays Res. 2012 Jul-Dec;6(2):15-23. doi:10.4103/0259-1162.108284 Lerch N, Mainetti C, Beretta-Piccoli BT, Harr T. Current perspectives on Stevens-Johnsons syndrome and toxic epidermal necrolysis. Clin Rev Allergy Immunol. 2018 Feb;54(1):147-76. doi:10.1007/s12016-017-8654-z Ruminski MA, Wisneski SS, Dugan SE. Stevens-Johnson syndrome: what a pharmacist should know. US Pharm. 2013;38(7):69-79. Meyer C, Behm N, Brown E, Copeland NK, Sklar MJ. An adverse drug reaction to trimethoprim-sulfamethoxazole revealing primary HIV: a case report and literature review. Case Rep Infect Dis. 2015;2015:691010. doi:10.1155/2015/691010 Platt D, Griggs RC. Use of acetazolamide in sulfonamide-allergic patients with neurologic channelopathies. Arch Neurol. 2012;69(4):527-9. doi:10.1001/archneurol.2011.2723 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 Feb:143(2):AB33. doi:10.1016/j.jaci.2018.12.102 American Academy of Allergy, Asthma & Immunology. Lack of cross-reactivity between sulfonamide antibiotics and nonantibiotic sulfonamides. May 16, 2017. Pharmacia & Upjohn Company. Package insert - Azulfidine (sulfasalazine). Updated 2009. Shah TJ, Moshirfar M, Hoopes PC. "Doctor, I have a sulfa allergy": Clarifying the myths of cross-reactivity. Ophthalmol Ther. 2018 Dec;7(2):211-5. doi:10.1007/s40123-018-0136-8