Sulfonamides and Trimethoprim (Systemic)

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 sulfonamide and trimethoprim combinations, 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], methazolamide [e.g., Neptazane]), or trimethoprim (e.g., Trimpex). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives (e.g., sulfites), or dyes.

Pregnancy - Sulfamethoxazole and trimethoprim combination has not been reported to cause birth defects or other problems in humans. However, studies in mice, rats, and rabbits have shown that some sulfonamides cause birth defects, including cleft palate and bone problems. Studies in rabbits have also shown that trimethoprim causes birth defects, as well as a decrease in the number of successful pregnancies. Sulfonamides are not recommended for use at the time of labor and delivery because these medicines may cause unwanted effects in the baby.

Breast-feeding - Sulfonamides and trimethoprim pass into the breast milk. These medicines are not recommended for use during breast-feeding. They may cause liver problems, anemia, and other unwanted effects in nursing babies, especially those with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Children - Sulfadiazine and trimethoprim combination should not be given to infants less than 3 months of age. Sulfamethoxazole and trimethoprim combination should not be given to infants less than 2 months of age unless directed by the child's doctor. These combinations may cause unwanted effects. In special situations, sulfamethoxazole and trimethoprim combination may be given to infants less than 2 months of age.

Older adults - Elderly people are especially sensitive to the effects of sulfonamide and trimethoprim combinations. 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 sulfonamide and trimethoprim combinations, it is especially important that your health care professional know if you are taking any of the following:

• Acetaminophen (e.g., Tylenol) (with long-term, high-dose use) or
• Amiodarone (e.g., Cordarone) or
• Anabolic steroids (nandrolone [e.g., Anabolin], oxandrolone [e.g., Anavar], oxymetholone [e.g., Anadrol], stanozolol [e.g., Winstrol]) or
• Androgens (male hormones) or
• Antithyroid agents (medicine for overactive thyroid) or
• Carbamazepine (e.g., Tegretol) or
• Carmustine (e.g., BiCNU) or
• Chloroquine (e.g., Aralen) or
• Dantrolene (e.g., Dantrium) or
• Daunorubicin (e.g., Cerubidine) or
• Disulfiram (e.g., Antabuse) or
• Divalproex (e.g., Depakote) or
• Estrogens (female hormones) or
• Etretinate (e.g., Tegison) or
• Gold salts (medicine for arthritis) or
• Mercaptopurine (e.g., Purinethol) or
• Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
• Oral contraceptives (birth control pills) containing estrogens or
• Other anti-infectives by mouth or by injection (medicine for infection) or
• Phenothiazines (acetophenazine [e.g., Tindal], chlorpromazine [e.g., Thorazine], fluphenazine [e.g., Prolixin], mesoridazine [e.g., Serentil], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], promazine [e.g., Sparine], promethazine [e.g., Phenergan], thioridazine [e.g., Mellaril], trifluoperazine [e.g., Stelazine], triflupromazine [e.g., Vesprin], trimeprazine [e.g., Temaril]) or
• Plicamycin (e.g., Mithracin) or
• Valproic acid (e.g., Depakene) - Use of sulfonamide and trimethoprim combinations with these medicines may increase the chance of side effects affecting the liver

• Acetohydroxamic acid (e.g., Lithostat) or
• Furazolidone (e.g., Furoxone) or
• Nitrofurantoin (e.g., Furadantin) or
• Primaquine or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) or
• Quinine (e.g., Quinamm) or
• Sulfoxone (e.g., Diasone) - Use of sulfonamide and trimethoprim combinations with these medicines may increase the chance of side effects affecting the blood

• Anticoagulants (blood thinners) or
• Digoxin (e.g., Lanoxin)
• Ethotoin (e.g., Peganone) or
• Mephenytoin (e.g., Mesantoin) or
• Methotrexate (e.g., Mexate) or
• Phenytoin (e.g., Dilantin) - Use of sulfonamide and trimethoprim combinations with these medicines may increase the chance of side effects of these medicines

• Antidiabetics, oral (diabetes medicine you take by mouth) - Use of oral antidiabetics with sulfonamide and trimethoprim combinations may increase the chance of side effects affecting the blood and/or the side effects of the oral antidiabetics

• Methenamine (e.g., Mandelamine) - Use of methenamine with sulfonamide and trimethoprim combinations may increase the chance of side effects of the sulfonamide

• Methyldopa (e.g., Aldomet) - Use of methyldopa with sulfonamide and trimethoprim combinations may increase the chance of side effects affecting the liver and/or the blood

Other medical problems - The presence of other medical problems may affect the use of sulfonamide and trimethoprim combinations. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia or other blood problems or
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency - Patients with these problems may have an increase in side effects affecting the blood

• Kidney disease or
• Liver disease - Patients with kidney and/or liver disease may have an increased chance of side effects

• Porphyria - This medicine may bring on an attack of porphyria