Bactrim Cold Sweats, Severe Headaches, Allergic to Sulfa Drugs, Benadryl, Stiff Neck Posted over a year ago I can't believe I am reading about the same thing I am going through.it helps me to know it's not just me. But be sure to tell your doctor if you have a sulfa allergy before taking any of these. Sulfa vs. Sulfite Allergy A sulfa allergy sounds like a sulfite allergy, but they’re very different. Allergic Reaction To Bactrim As with any other antibiotics and drugs, bactrim can also cause host of allergic symptoms in a person who is allergic to sulfa drug. If the patient has passed history of sulfa allergy, it is very important for him to inform his doctor about the allergy. If you have an allergy to sulfamethoxazole, trimethoprim, or any other part of Bactrim DS (sulfamethoxazole and trimethoprim tablets). If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Note: This document contains side effect information about sulfamethoxazole / trimethoprim. Some of the dosage forms listed on this page may not apply to the brand name Bactrim. Bactrim (sulfamethoxazole and trimethoprim) DS is a combination of two antibiotics used to treat urinary tract infections, acute otitis media, bronchitis, Shigellosis, Pneumocystis pneumonia, traveler's diarrhea, methicillin-resistant Staphylococcus aureus , and other bacterial infections susceptible to this antibiotic. Find information about common, infrequent and rare side effects of Bactrim DS Oral. One type of serious allergic reaction to Bactrim is called Stevens-Johnson syndrome, according to the Merck Manual. With Stevens-Johnson syndrome, patients develop a fever, headache and general fatigue as well as characteristic red bumps on their skin. After my first dose of bactrim I took, I developed a stiff neck, fever, and serve headache (almost identical of PTC symptoms, which I never usually get) The doctor took me off bactrim and prescribed keflex. Bactrim is the brand name of the generic antibiotic sulfamethoxazole trimethoprim (sometimes called co-trimoxazole). The drug is a combination of two antibiotics: It's one part trimethoprim (a.