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Sulfonamides  (Systemic)

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Brand Names

Some commonly used brand names are:

In the U.S.—

  • Gantanol3
  • Gantrisin4
  • Thiosulfil Forte2
  • Urobak3

In Canada—

  • Apo-Sulfamethoxazole3
  • Apo-Sulfisoxazole4
  • Novo-Soxazole4
  • Sulfizole4

Note:

For quick reference, the following sulfonamides are numbered to match the corresponding brand names.
This information applies to the following medicines:
1.  Sulfadiazine (sul-fa-DYE-a-zeen)
2.  Sulfamethizole (sul-fa-METH-a-zole)
3.  Sulfamethoxazole (sul-fa-meth-OX-a-zole)§
4.  Sulfisoxazole (sul-fi-SOX-a-zole)
‡  Generic name product may be available in the U.S.
§  Generic name product may be available in Canada
*  Not commercially available in the U.S.
†  Not commercially available in Canada

Category


Description

Sulfonamides (sul-FON-a-mides) or sulfa medicines are used to treat infections. They will not work for colds, flu, or other virus infections.

Sulfonamides are available only with your doctor's prescription, in the following dosage forms:



Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfonamides, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sulfa medicines, furosemide (e.g., Lasix) or thiazide diuretics (water pills), oral antidiabetics (diabetes medicine you take by mouth), glaucoma medicine you take by mouth (for example, acetazolamide [e.g., Diamox], dichlorphenamide [e.g., Daranide], or methazolamide [e.g., Neptazane]). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in pregnant women. However, studies in mice, rats, and rabbits have shown that some sulfonamides cause birth defects, including cleft palate and bone problems. Sulfonamides are not recommended for use at the time of labor and delivery. These medicines may cause unwanted effects in the baby.

Breast-feeding—Sulfonamides pass into the breast milk. This medicine is not recommended for use during breast-feeding. It may cause liver problems, anemia, and other unwanted effects in nursing babies, especially those with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Children—Sulfonamides should not be given to infants under 2 months of age unless directed by the child's doctor, because they may cause unwanted effects.

Older adults—Elderly people are especially sensitive to the effects of sulfonamides. Severe skin problems and blood problems may be more likely to occur in the elderly. These problems may also be more likely to occur in patients who are taking diuretics (water pills) along with this medicine.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking sulfonamides, it is especially important that your health care professional knows if you are taking any of the following:

Other medical problems—The presence of other medical problems may affect the use of sulfonamides. Make sure you tell your doctor if you have any other medical problems, especially:


Proper Use of This Medicine

Sulfonamides should not be given to infants less than 2 months of age unless directed by the patient's doctor because sulfonamides may cause serious unwanted effects.

Sulfonamides are best taken with a full glass (8 ounces) of water. Several additional glasses of water should be taken every day, unless otherwise directed by your doctor. Drinking extra water will help to prevent some unwanted effects of sulfonamides.

For patients taking the oral liquid form of this medicine:

To help clear up your infection completely, keep taking this medicine for the full time of treatment, even if you begin to feel better after a few days. If you stop taking this medicine too soon, your symptoms may return.

This medicine works best when there is a constant amount in the blood or urine. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times day and night. If you need help in planning the best times to take your medicine, check with your health care professional.

Dosing—

The dose of these medicines will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. This will help to keep a constant amount of medicine in the blood or urine. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:


Precautions While Using This Medicine

It is very important that your doctor check your progress at regular visits. This medicine may cause blood problems, especially if it is taken for a long time.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Sulfonamides may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.

Sulfonamides may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:

If you have a severe reaction from the sun, check with your doctor.

This medicine may also cause some people to become dizzy. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert . If this reaction is especially bothersome, check with your doctor.


Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Also, check with your doctor as soon as possible if the following side effect occurs:

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.


Revised: 08/25/1995

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