March 21, 2017

Sulfamethoxazole tablets

What are sulfamethoxazole tablets?

SULFAMETHOXAZOLE (Gantanol®) is a sulfonamide antibiotic. Sulfamethoxazole stops the growth of certain bacteria. It treats urinary tract infections and some other infections. Generic sulfamethoxazole tablets are available.

What should my health care professional know before I take sulfamethoxazole?

They need to know if you have any of these conditions:

  • asthma

  • blood disorders

  • dental disease

  • glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency)

  • kidney disease

  • liver disease

  • porphyria

  • vitamin deficiency

  • other chronic illness

  • an unusual or allergic reaction to 'sulfa drugs,' sulfite preservatives, furosemide or thiazide diuretics (water pills), oral diabetes medicines, or other medicines, foods, dyes, or preservatives

  • pregnant or trying to get pregnant

  • breast-feeding

How should I take this medicine?

Take sulfamethoxazole tablets by mouth. Follow the directions on the prescription label. Swallow tablets whole with a full glass of water. Take your doses at regular intervals. Do not take your medicine more often than directed. Finish the full course prescribed by your prescriber or health care professional even if you think your condition is better. Do not stop taking except on your prescriber's advice.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses. There should be an interval of at least 6 to 8 hours between doses.

What drug(s) may interact with sulfamethoxazole?

  • cyclosporine

  • doxercalciferol

  • medicines for diabetes that are taken by mouth

  • methenamine

  • methotrexate

  • phenylbutazone

  • phenytoin

  • ramelteon

  • sulfinpyrazone

  • voriconazole

  • warfarin

  • water pills

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking sulfamethoxazole?

Tell your prescriber or health care professional if your symptoms do not improve in 2 or 3 days, or if you develop a skin rash.

If you are taking this medicine for a long time you must visit your prescriber or health care professional for regular blood checks.

Sulfamethoxazole can cause blood problems. This can mean slow healing and a risk of infection. Problems can arise if you need dental work, and in the day to day care of your teeth. Try to avoid damage to your teeth and gums when you brush or floss your teeth.

If you are a diabetic using insulin or oral hypoglycemics (like glyburide) monitor your blood glucose carefully. If you get an unusual reaction stop using sulfamethoxazole at once and call your prescriber or health care professional for advice.

Drink several glasses of water a day. This will help to reduce possible kidney problems.

Keep out of the sun, or wear protective clothing outdoors and use a sunscreen. Do not use sun lamps or sun tanning beds or booths.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how sulfamethoxazole affects you. To reduce the risk of dizzy or fainting spells, do not sit or stand up quickly, especially if you are an older patient.

If you are going to have surgery, tell your prescriber or health care professional that you are using sulfamethoxazole.

What side effects may I notice from taking sulfamethoxazole?

Elderly patients are more likely to get side effects.

Side effects that you should report to your prescriber or health care professional as soon as possible:

  • blood in urine

  • bluish fingernails or lips

  • dark yellow or brown urine

  • cough

  • difficulty breathing

  • increased sensitivity to the sun or ultraviolet light

  • joint aches or pains

  • less urine passed

  • muscle aches or pains

  • pain or difficulty passing urine

  • redness, blistering, peeling or loosening of the skin, including inside the mouth

  • skin rash, hives, or itching

  • sore mouth

  • sore throat, fever

  • swelling of the neck

  • unusual bruising or bleeding

  • unusual tiredness or weakness

  • yellowing of the eyes or skin

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):

  • diarrhea

  • drowsiness, dizziness

  • headache

  • loss of appetite

  • nausea, vomiting

  • stomach pain

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.


March 21, 2017


U.S. FDA-approved Package Insert