What are sulfonamides, and what are they used for?
Sulfonamides (sulfa drugs) are drugs that are derived from sulfanilamide, a sulfur-containing chemical. Most sulfonamides are antibiotics, but some are prescribed for treating ulcerative colitis. Sulfonamide antibiotics work by disrupting the production of dihydrofolic acid, a form of folic acid that bacteria and human cells use for producing proteins.
What are the side effects of sulfonamides?
Sulfonamides may cause:
Sulfonamides should be stopped at the first appearance of a skin rash before the rash becomes severe.
Serious rashes include:
- Stevens-Johnson syndrome, which includes symptoms like:
- aching joints,
- aching muscles,
- redness,
- blistering, and
- peeling of the skin
- Toxic epidermal necrolysis, which includes symptoms like:
- difficulty in swallowing,
- peeling,
- redness,
- loosening, and
- blistering of the skin.
Sulfonamides also may cause sensitivity to the sun that leads to extensive sunburn after exposure to sunlight (photosensitivity). Patients receiving sulfonamides should avoid excessive exposure to sunlight and should wear sunscreen.
Other rare side effects include liver damage, low white blood cell count (leucopenia), low platelet count (thrombocytopenia), and anemia. Formation of urinary crystals which may damage the kidney and may cause blood. Adequate hydration is needed to prevent the formation of urinary crystals.
What are examples of sulfonamides available in the US?
Examples of sulfonamides include:
- sulfamethoxazole/trimethoprim (Bactrim, Bactrim DS, Septra, Septra DS)
- sulfasalazine (Azulfidine, Sulfazine)
- sulfisoxazole (Truxazole)
Many of these drugs are available only in generic forms.
What drugs interact with sulfonamides?
The increased metabolism (break-down and elimination) of cyclosporine by the liver caused by sulfonamides (reduces the effectiveness of cyclosporine and can add to the kidney damage caused by cyclosporine.
All sulfonamides can crystallize in the urine when the urine is acidic. Since methenamine (Hiprex, Urex, Mandelamine) causes acidic urine, it should not be used with sulfonamides.
Blood levels of digoxin may increase blood levels of digoxin (Lanoxin) and possibly lead to serious toxic effects.
Anemia, due to a reduction in folic acid, can occur in persons receiving sulfonamides in combination with divalproex, valproic acid (Depakote, Depakote ER, Depakene, Depacon, Stavzor), methotrexate (Rheumatrex, Trexall), pyrimethamine, triamterene, or trimetrexate.
Increased blood levels of potassium may occur when sulfamethoxazole/trimethoprim is combined with angiotensin converting enzyme (ACE) inhibitors.

SLIDESHOW
Bacterial Infections 101: Types, Symptoms, and Treatments See SlideshowWhat formulations of sulfonamides are available?
Sulfonamides are available as tablets, injections, and oral solutions.
Pregnancy and breastfeeding
Use of sulfonamides may cause bilirubin to be displaced from proteins in the infant's blood. Displacement of bilirubin can lead to jaundice and a dangerous condition called kernicterus in the infant. For this reason, sulfamethoxazole/ trimethoprim should not be used near term (late in pregnancy) among women.
Sulfonamides (for example, sulfamethoxazole/trimethoprim) should not be used while nursing because sulfamethoxazole is excreted in breast milk and can cause kernicterus.
Health News
- CDC Warns of Potentially Fatal Bacterial Illness on U.S. Gulf Coast
- Helping Others as Volunteers Helps Kids 'Flourish': Study
- FDA Approves Pfizer's RSV Shot for Older Adults
- What to Do When Tough-to-Treat Lymphoma Strikes During Pregnancy
- Rate of Pregnant U.S. Women Who Have Diabetes Keeps Rising
More Health News ยป
Summary
Sulfonamides are a class of drugs from a sulfur-containing chemical (sulfanilamide). Examples of sulfonamides include sulfamethoxazole/trimethoprim (Bactrim, Bactrim DS, Co-trimoxazole, Septra, Septra DS, Cotrim, SMZ-TMP, SMZ-TMP DS, Sulfatrim); sulfasalazine (Azulfidine, Sulfazine); and sulfisoxazole (Truxazole, Gantrisin). Some of these drugs are available only in generic forms. Side effects of sulfonamides may include dizziness, lethargy, diarrhea, nausea, vomiting, headache, serious skin rashes and anorexia. Sulfonamides are not recommended for women who are pregnant or breastfeeding. Side effects and drug interactions should be reviewed prior to taking this medication.
Multimedia: Slideshows, Images & Quizzes
-
Bacterial Infections 101: Types, Symptoms, and Treatments
Get more information on bacterial skin infections, which bacteria cause food poisoning, sexually transmitted bacteria, and more....
-
Ulcerative Colitis: Symptoms, Diet, Treatment, Causes
Ulcerative Colitis is a form of inflammatory bowel disease and is slightly different than Crohn's disease. Learn the causes,...
-
Ulcerative Colitis Quiz: Diet, Symptoms & Treatment
What is ulcerative colitis and what risks are associated with suffering over the long term? Take this Ulcerative Colitis Quiz to...
-
Nutritional Tips for Children and Teens with Ulcerative Colitis
The symptoms of UC make it challenging for kids to get the proper nutrients. Try these tactics to help your child avoid symptom...
-
Ulcerative Colitis Surgery -- What to Expect
See the different surgeries used to treat ulcerative colitis. WebMD shows you when it may be needed, what is involved, and...
-
Celebrities With Ulcerative Colitis (UC)
Anybody can get ulcerative colitis. Here are some well-known people who were diagnosed with UC.
Related Disease Conditions
-
Urinary Tract Infection (UTI)
A urinary tract infection (UTI) is an infection of the bladder, kidneys, ureters, or urethra. E. coli, a type of bacteria that lives in the bowel and near the anus, causes most UTIs. UTI symptoms include pain, abdominal pain, mild fever, urinary urgency, and frequency. Treatment involves a course of antibiotics.
-
Middle Ear Infection (Otitis Media)
A middle ear infection (otitis media) can cause earache, temporary hearing loss, and pus drainage from the ear. It is most common in babies, toddlers, and young children. Learn about causes and treatment.
-
Rheumatoid Arthritis (RA)
Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body.
-
Pneumonia
Pneumonia is inflammation of the lungs caused by fungi, bacteria, or viruses. Symptoms and signs include cough, fever, shortness of breath, and chills. Antibiotics treat pneumonia, and the choice of the antibiotic depends upon the cause of the infection.
-
Ulcerative Colitis Diet Plan
An ulcerative colitis diet plan can help a person with the disease avoid foods and drinks that trigger flares. There also are foods that can soothe ulcerative colitis symptoms during a flare. Types of ulcerative colitis plans include a high-calorie diet, a lactose-free diet, a low-fat diet, a low-fiber diet (low-residue diet), or a low-salt diet. Self-management of ulcerative colitis using healthy lifestyle habits and a nutrient rich diet can be effective in management of the disease. Learn what foods to avoid that aggravate, and what foods help symptoms of the disease and increase bowel inflammation.
-
Impetigo
Impetigo is a contagious skin infection caused by staph and strep bacteria. There are two types of impetigo: nonbullous and bullous. Symptoms of nonbullous impetigo include small blisters on the nose, face, arms, or legs and possibly swollen glands. Bullous impetigo signs include blisters in various areas, particularly in the buttocks area. Treatment involves gentle cleansing, removing the crusts of popped blisters, and the application of prescription-strength mupirocin antibiotic ointment.
-
Ulcerative Colitis
Ulcerative colitis is a chronic inflammation of the colon. Symptoms and signs include abdominal pain, diarrhea, and rectal bleeding. Ulcerative colitis is closely related to Crohn's disease, and together they are referred to as inflammatory bowel disease. Treatment depends upon the type of ulcerative colitis diagnosed.
-
Chronic Bronchitis
Chronic bronchitis is a cough that occurs daily with production of sputum that lasts for at least 3 months, 2 years in a row. Causes of chronic bronchitis include cigarette smoking, inhaled irritants, and underlying disease processes (such as asthma, or congestive heart failure). Symptoms include cough, shortness of breath, and wheezing. Treatments include bronchodilators and steroids. Complications of chronic bronchitis include COPD and emphysema.
-
Crohn's Disease
Crohn's disease is a chronic inflammatory disease, primarily involving the small and large intestine, but which can affect other parts of the digestive system as well. Abdominal pain, diarrhea, vomiting, fever, and weight loss are common symptoms and signs.
-
What Is the Life Expectancy of Someone With Ulcerative Colitis?
Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that affects the inner lining of the large intestine (large bowel) leading to erosion and ulcers. It is a lifelong illness with no specific cause or cure.
-
When Do You Need Hospitalization for Ulcerative Colitis?
Ulcerative colitis is an inflammatory bowel disease that can be life-threatening when the symptoms flare up. You need ulcerative colitis hospitalization if you have more than six bowel movements per day, blood in your stool, high temperature and heart rate, and severe abdominal pain.
-
How Long Does an Ulcerative Colitis Flare-Up Last?
An ulcerative colitis flare-up can last a few days or a few weeks and then be followed by a remission that lasts for months or even years. How long a flare-up lasts depends on the severity of the disease, triggers, and medication compliance.
-
Crohn's Disease vs. Ulcerative Colitis
Crohn's disease and ulcerative colitis are diseases that cause inflammation of part of or the entire digestive tract (GI). Crohn's affects the entire GI tract (from the mouth to the anus), while ulcerative colitis or ulcerative colitis only affects the large and small intestine and ilium. Researchers do not know the exact cause of either disease. About 20% of people with Crohn's disease also have a family member with the disease. Researchers believe that certain factors may play a role in causing UC. Both Crohn's disease and ulcerative colitis are a type of inflammatory bowel disease or IBD. Crohn's disease and ulcerative colitis both have similar symptoms and signs, for example, nausea, loss of appetite, fatigue, weight loss, episodic and/or persistent diarrhea, fever, abdominal pain and cramping, rectal bleeding, bloody stools, joint pain and soreness, eye redness, or pain. Symptoms unique to Crohn’s disease include anemia and skin changes. Symptoms of unique to ulcerative colitis include certain rashes, and an urgency to defecate (have a bowel movement). Doctors diagnose both diseases with similar tests and procedures. While there is no cure for either disease, doctors and other health care professionals can help you treat disease flares, and manage your Crohn's or ulcerative colitis with medication, diet, nutritional supplements, and/or surgery.
-
How Do I Know if My Ulcerative Colitis Is Flaring?
Ulcerative colitis happens when irritation and open sores appear in the large intestine. You know ulcerative colitis is flaring if you experience bloody stools, nausea and vomiting, frequent bowel movements, and other symptoms.
-
What Foods Trigger Ulcerative Colitis?
Ulcerative colitis (or inflammatory bowel disease) is a difficult condition to live with. Foods that trigger ulcerative colitis include raw green vegetables, lactose, sugar alcohol, caffeine, alcohol, whole grains, and foods high in fat.
-
What Does Your Stool Look Like With Ulcerative Colitis?
Ulcerative colitis (UC) is a disease that involves the inner lining of the large bowel. It causes abdominal pain and bleeds due to erosions and ulcers all over the large intestine and rectum.
-
What Is the Best Diet for Someone With Ulcerative Colitis?
Ulcerative colitis is a chronic condition in which your colon and rectum are often inflamed. The best diet for someone with ulcerative colitis is one that includes lean protein, low-fiber fruit, refined grains, cooked vegetables, probiotic-rich foods, and calcium-rich foods.
-
Is Pancolitis the Same as Ulcerative Colitis?
Pancolitis is a form of ulcerative colitis (UC) that inflames the entire large intestine. Living with pancolitis often requires medical treatment and lifestyle changes.
-
Can Ulcerative Colitis Be Healed?
Ulcerative colitis is a type of inflammatory bowel disease. While there's no known ulcerative colitis cure, treatment can help you manage your symptoms and let you lead a full life.
-
Is Ulcerative Colitis Curable?
Ulcerative colitis is an inflammatory bowel disease (IBD) that affects the inner lining of the large intestine (large bowel or colon) leading to erosion and ulcers. It is also associated with various manifestations outside of the colon, such as inflammation of the eyes, joints, skin, and lungs. Ulcerative colitis is a lifelong illness with no specific cause or cure. Patients have repeated cycles of flare-ups and disappearance of the disease.
-
Can Ulcerative Colitis Be Cured With Surgery?
Ulcerative colitis is a chronic inflammatory condition of the colon (the large bowel) characterized by frequent bloody diarrhea (10-30 episodes) throughout the day. Medicines can only reduce the intensity of its symptoms and surgery is the only option to cure it.
-
What Is the Best Treatment for Ulcerative Colitis?
Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) that affects the inner lining of the large intestine (large bowel) leading to erosion and ulcers. It is a lifelong illness with no specific cause or cure. Patients have repeated cycles of flare-ups and remission with potential extraintestinal (beyond the bowel) manifestations, such as joint pain, eye pain, and skin rashes.
-
What Is the Best Medicine for Ulcerative Colitis?
Treatment strategies for ulcerative colitis (UC) vary from person to person. Your doctor will base recommendations for medication on the intensity of your symptoms and severity of the disease.
-
Is Ulcerative Colitis an Autoimmune Disease?
Ulcerative colitis (UC) is considered to be an autoimmune disease. With autoimmune disorders, your immune system goes awry and attacks your own body instead of defending it from infections and illnesses.
-
What Are the First Symptoms of Ulcerative Colitis?
The first symptoms and signs of ulcerative colitis (UC) may include persistent diarrhea, loose or bloody stools, cramp-like abdominal pain, and general feelings of being unwell, bloated, or constipated.
-
How Serious Is Ulcerative Colitis?
Ulcerative colitis (UC) is a lifelong disease with constant periods of flare-ups and remissions (periods without symptoms, which may last for weeks or years). Presently, there is no permanent medical cure for it, but there are various medications that can provide symptomatic relief, reduce inflammation and manage flare-ups.
-
How Do You Diagnose Ulcerative Colitis?
Ulcerative colitis is a condition that causes blood stool, diarrhea, rectal pain, and other symptoms. Ulcerative colitis is diagnosed with blood tests, stool tests, and imaging tests.
-
What Happens When You Have Ulcerative Colitis?
Ulcerative colitis is a systemic disease that mainly manifests as intestinal ulcers. The ulcers may result in bleeding and cause bloody stools. Excessive bleeding can lead to anemia.
Treatment & Diagnosis
- Ulcerative Colitis FAQs
- Drugs: The Most Common Medication Errors
- Medication Disposal
- Dangers of Mixing Medications
- Drugs: Buying Prescription Drugs Online Safely
- Does Stress Cause Ulcerative Colitis?
- Does IBS Cause Crohn's Disease or Ulcerative Colitis?
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
Prevention & Wellness
Health Solutions From Our Sponsors

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.