Medication Guide App

SULFONAMIDES AND PHENAZOPYRIDINE (Systemic)

Some commonly used brand names are:

In the U.S.—

  • Azo Gantanol 1
  • Azo Gantrisin 2
  • Azo-Sulfamethoxazole 1
  • Azo-Sulfisoxazole 2
  • Azo-Truxazole 2
  • Sul-Azo 2

In Canada—

  • Azo Gantrisin 2

Note:

For quick reference, the following sulfonamides and phenazopyridine combinations are numbered to match the corresponding brand names.

This information applies to the following medicines:
1. Sulfamethoxazole and Phenazopyridine (sul-fa-meth-OX-a-zole and fen-az-oh-PEER-i-deen)
2. Sulfisoxazole and Phenazopyridine (sul-fi-SOX-a-zole and fen-az-oh-PEER-i-deen)
† Not commercially available in Canada
‡ Generic name product may be available in the U.S.

Category

  • Antibacterial-analgesic, urinary tract—Sulfamethoxazole and Phenazopyridine; Sulfisoxazole and Phenazopyridine

Description

Sulfonamides and phenazopyridine, combination products containing a sulfa medicine and a urinary pain reliever, are used to treat infections of the urinary tract and to help relieve the pain, burning, and irritation of these infections.

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

  • Oral
  • Sulfamethoxazole and Phenazopyridine
    • Tablets (U.S.)
  • Sulfisoxazole and Phenazopyridine
    • Tablets (U.S. and Canada)

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 and phenazopyridine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to any of the 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 phenazopyridine (e.g., Pyridium). 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 humans. Studies in mice, rats, and rabbits have shown that some sulfonamides cause birth defects, including cleft palate and bone problems. In addition, sulfa medicines may cause liver problems in newborn infants. Therefore, use is not recommended during pregnancy. Phenazopyridine has not been shown to cause birth defects in animal studies.

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—This medicine has been tested in a limited number of children 12 years of age or older. In effective doses, the medicine has not been shown to cause different side effects or problems in children than it does in adults.

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 and phenazopyridine, 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
  • Hydroxychloroquine (e.g., Plaquenil) or
  • Mercaptopurine (e.g., Purinethol) or
  • Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
  • Oral contraceptives (birth control pills) containing estrogen 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 sulfonamides and phenazopyridine combination with these medicines may increase the chance of side effects affecting the liver
  • Acetohydroxamic acid (e.g., Lithostat) or
  • Dapsone 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) or
  • Vitamin K (e.g., AquaMEPHYTON, Synkayvite)—Use of sulfonamides and phenazopyridine combination with these medicines may increase the chance of side effects affecting the blood
  • Anticoagulants (blood thinners) or
  • Ethotoin (e.g., Peganone) or
  • Heparin or
  • Mephenytoin (e.g., Mesantoin)—Use of sulfonamides and phenazopyridine combination 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 sulfonamides and phenazopyridine combination may increase the chance of side effects affecting the blood and/or the side effects of oral antidiabetics
  • Methenamine (e.g., Mandelamine) or
  • Methenamine-containing medicines (e.g., Urised)—Use of these medicines with sulfonamides and phenazopyridine combination may increase the chance of side effects of the sulfonamides
  • Methotrexate (e.g., Mexate)—Use of methotrexate with sulfonamides and phenazopyridine combination may increase the chance of side effects affecting the liver and/or the side effects of methotrexate
  • Methyldopa (e.g., Aldomet)—Use of methyldopa with sulfonamides and phenazopyridine combination may increase the chance of side effects affecting the liver and/or the blood
  • Phenytoin (e.g., Dilantin)—Use of phenytoin with sulfonamides and phenazopyridine combination may increase the chance of side effects affecting the liver and/or the side effects of phenytoin

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

  • Anemia or other blood problems or
  • Glucose-6-phosphate dehydrogenase deficiency (lack of G6PD enzyme)—Patients with these problems may have an increase in side effects affecting the blood
  • Hepatitis or other liver disease or
  • Kidney disease—Patients with kidney disease or liver disease may have an increased chance of side effects
  • Porphyria—Use of sulfonamides may bring on an attack of porphyria

Proper Use of This Medicine

Sulfonamides and phenazopyridine combinations 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 (e.g., kidney stones) of the sulfonamide. This medicine may be taken with meals or following meals if it upsets your stomach.

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 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 . For example, if you are to take 4 doses a day, the doses should be spaced about 6 hours apart. If this interferes with your sleep or other daily activities, or if you need help in planning the best times to take your medicine, check with your health care professional.

Dosing—The dose of sulfonamides and phenazopyridine combination may 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 sulfonamides and phenazopyridine combination. Your dose may be different if you have kidney disease. If your dose is different, do not change it unless your doctor tells you to do so.

  • For sulfamethoxazole and phenazopyridine combination :
    • Adults and children 12 years of age and older: 2 grams of sulfamethoxazole and 400 mg of phenazopyridine for the first dose, then 1 gram of sulfamethoxazole and 200 mg of phenazopyridine every twelve hours for up to two days.
    • Children up to 12 years of age: This medication is not recommended.
  • For sulfisoxazole and phenazopyridine combination :
    • Adults and children 12 years of age and older: 2 to 3 grams of sulfisoxazole and 200 to 300 mg of phenazopyridine for the first dose, then 1 gram of sulfisoxazole and 100 mg of phenazopyridine every twelve hours for up to two days.
    • Children up to 12 years of age: This medication is not recommended.

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 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:

  • Keep out of the reach of children.
  • Store away from heat and direct light.
  • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
  • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

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:

  • Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
  • Wear protective clothing, including a hat. Also, wear sunglasses.
  • Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
  • Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
  • Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction, 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.

This medicine causes the urine to turn reddish orange . This is to be expected while you are using this medicine and is not harmful. Also, the medicine may stain clothing. If you have any questions about removing the stain, check with your health care professional.

For diabetic patients:

  • This medicine may cause false test results with some urine sugar tests and urine ketone tests . Check with your doctor before changing your diet or the dosage of your diabetes medicine.

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:

More common

Itching; skin rash

Less common

Aching of joints and muscles; blue or blue-purple discoloration of skin; difficulty in swallowing; pale skin; redness, blistering, peeling, or loosening of skin; shortness of breath; sore throat and fever; unusual bleeding or bruising; unusual tiredness or weakness; yellow eyes or skin

Rare

Blood in urine; greatly increased or decreased frequency of urination or amount of urine; increased thirst; lower back pain; pain or burning while urinating; swelling of front part of neck

In addition to the side effects listed above, check with your doctor as soon as possible if the following side effect occurs:

More common

Increased sensitivity of skin to sunlight

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:

More common

Diarrhea; dizziness; headache; loss of appetite; nausea or vomiting; tiredness

Less common

Indigestion; stomach cramps or pain

This medicine causes the urine to become reddish orange. This side effect does not require medical attention.

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

Revised: 02/01/1993

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