What Are the Uses and Side Effects of Sulfonamides?

Rosanna Sutherby, PharmD
·7 min read
1

Medically reviewed by Femi Aremu, PharmDMedically reviewed by Femi Aremu, PharmD

Sulfonamide drugs are a group of antibiotics used to treat or prevent certain bacterial infections in humans and animals. They work by preventing bacteria from growing and multiplying.

Sulfonamides have a wide range of uses that include treating urinary tract infections (UTIs) and preventing or treating skin infections due to second- or third-degree burns.

This article discusses what sulfonamides are, their uses, and possible side effects.

<p>Getty Images | miniseries</p>

Getty Images | miniseries

Understanding Sulfonamides

Sulfonamides have a number of uses. They're considered broad-spectrum antibiotics, which means they can treat infections caused by several types of bacteria. Sulfonamides work by interfering with the process by which many bacteria make DNA.

How Sulfonamides Work

Sulfonamides are considered bacteriostatic antibiotics, which means they treat bacterial infections by stopping bacterial multiplication and growth.

Sulfonamides do this by blocking bacteria's ability to create folic acid. This is a vitamin they use to make DNA. When bacteria are unable to make DNA, they cannot multiply and eventually die.

Sulfonamide Uses

Sulfonamide antibiotics can be used to treat several bacterial infections, including:

Certain sulfonamides are also used to treat symptoms of inflammatory conditions, such as ulcerative colitis and rheumatoid arthritis.

Examples of Sulfonamides

The following are examples of sulfonamides currently available in the United States:

Mafenide

Mefanide (sold under the brand name Sulfamylon) is a cream you apply to the skin. It is used to prevent and treat skin infections caused by burn wounds. The cream is applied to the affected skin once or twice per day after cleaning the wound.

Silver Sulfadiazine

Silver sulfadiazine (sold as the brand Silvadene) is another cream used to treat or prevent skin infections related to burns. As with Sulfamylon, silver sulfadiazine is applied once or twice daily after cleansing the burn wound.

Sulfacetamide

Sulfacetamide (brands include Klaron and Ovace) is available in several forms to treat different types of infections. It comes as a lotion you apply to your skin twice daily to treat acne. This medication also comes as an eye drop and eye ointment used to treat certain eye infections.

Sulfacetamide ointment is used to treat bacterial conjunctivitis, which is also known as pink eye. When using this ointment, you typically apply a small amount to the area between your eye and your lower eyelid every three to four hours and at bedtime. Your healthcare provider will prescribe your dosage based on the severity of your infection. In some cases, they may prescribe sulfacetamide eye ointment for use along with the eye drops.

Sulfacetamide eye drops can be used to treat conjunctivitis or trachoma, which is a chlamydia infection in the eyes.

For conjunctivitis, the dosage is usually one or two drops into the affected eye or eyes every two to three hours. For trachoma, the recommended dosage is two drops into the affected eye or eyes every two hours. With this type of infection, your healthcare provider will likely prescribe another antibiotic that you take by mouth along with sulfacetamide eye drops.

Sulfamethoxazole

Sulfamethoxazole (brands include Bactrim, Septra, and Sulfatrim) is available as a combination medication with another antibiotic called trimethoprim. Sulfamethoxazole with trimethoprim comes in both generic and brand forms. Available brand names include:

  • Bactrim

  • Bactrim DS

  • Septra

  • Septra DS

  • Sulfatrim Pediatric suspension

The combination drug comes in liquid and tablet forms that you take by mouth. It also comes as a liquid to be injected into your vein over a period of time.

Sulfamethoxazole with trimethoprim is used to treat several types of bacterial infections, including:

Dosing for sulfamethoxazole with trimethoprim is based on your condition and the form of the medication your healthcare provider prescribes.

Sulfasalazine

Sulfasalazine is not used as an antibiotic. Instead, it reduces inflammation and is used to treat symptoms of ulcerative colitis and rheumatoid arthritis. Sulfasalazine is available as a tablet that you take by mouth. It comes in a generic version and a brand form called Azulfidine.

The dosage of sulfasalazine varies based on your age and the severity of your condition. In general, this medication is typically taken three to six times per day.

What Are the Side Effects of Sulfonamides?

Side effects can vary based on the type and form of sulonamide medication you are using.

The following are general examples of potential sulfonamide side effects:

It's also possible to experience eye or skin irritation from sulfonamides that you use in your eyes or on your skin.

Although rare, sulfonamides may also cause more serious side effects, such as severe skin reactions. These can include:

Stevens-Johnson syndrome is a serious reaction that affects the skin and mucous membranes, including the inside of your mouth and the lining of your airways. TEN is a more severe version of Stevens-Johnson syndrome.

Symptoms of Stevens-Johnson syndrome or TEN may be mild at first, but they may become more serious if not treated. Initial symptoms include fever and other flu-like symptoms. After a few days, you may have more serious symptoms, such as:

  • Irritation and redness on the inside of the eyelids

  • Peeling and blistering of the skin or genital areas

  • Trouble breathing

  • Trouble swallowing

Stevens-Johnson syndrome and TEN are both potentially life-threatening reactions that require emergency medical care. Be sure to seek immediate medical attention if you have symptoms of these reactions while taking a sulfonamide drug.

Interactions

Some medications may affect sulfonamides negatively. These can vary based on the specific sulfonamide you take or use. In general, sulfonamides that are taken by mouth or given by injection are more likely to cause interactions than sulfonamides used on the skin or in the eyes.

Examples of medications that can interact with sulfonamides include:

Keep in mind that interactions may differ between sulfonamides. Be sure to tell your healthcare provider all the medications you take before you start treatment with a sulfonamide. They can decide if sulfonamides are safe to take with your medications.

Precautions

Sulfonamides may not be safe for everyone. They may worsen certain conditions or increase the risk of serious side effects. In some cases, sulfonamides may be used cautiously. For some people, it's best to avoid certain sulfonamide drugs.

Before you start treatment with a sulfonamide, let your healthcare provider know if you have:

Sulfonamides also may not be safe to take if you have a folate deficiency (low vitamin B9 level). Certain factors can increase your risk of having a folate deficiency. These include:

  • Being age 65 years or older

  • Having chronic alcohol use disorder

  • Having conditions that affect how you absorb nutrients from food

  • Taking certain seizure medications

It's important to talk with your healthcare provider about your health history before you take any sulfonamides. Sulfonamide contraindications and precautions may differ between sulfonamide drugs. This means that one sulfonamide may not be safe to take if you have a certain condition, but a different one may be used with caution.

Your healthcare provider can help you decide which sulfonamides are a safe option for you.

Summary

Sulfonamides are a group of antibiotics used to treat or prevent a wide range of infections, including skin, eye, and ear infections. They can also treat other infections, such as UTIs, pneumonia, and traveler's diarrhea.

It's important to talk with your healthcare provider about all the medications you take and your health history before you start treatment with a sulfonamide drug. Certain medications and health conditions may negatively affect some sulfonamides. Talk with your healthcare provider if you want to learn more about sulfonamide drugs. They can help you decide whether these drugs are effective and safe for your condition.

Read the original article on Verywell Health.