Do not give this medicine to infants or children under 12 years of age unless otherwise directed by your doctor.

Trimethoprim may be taken on an empty stomach or, if it upsets your stomach, it may be taken with food.

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 body. 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 2 doses a day, the doses should be spaced about 12 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 trimethoprim 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 trimethoprim. 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.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking trimethoprim.

• For the treatment of urinary tract infections :
  • Adults and children 12 years of age and older: 100 milligrams every twelve hours for ten days, or 200 milligrams once a day for ten days.
  • Children up to 12 years of age: Dose must be determined by the doctor.

Missed dose

If you do miss a dose of this medicine, take it as soon as possible. This will help to keep a constant amount of medicine in the body. 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• Do not keep outdated medicine or medicine no longer needed.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.

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 trimethoprim, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to trimethoprim. 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 rats have shown that trimethoprim causes birth defects. Studies in rabbits have shown that trimethoprim causes a decrease in the number of successful pregnancies. However, in the few reports where trimethoprim was taken by pregnant women, trimethoprim has not been reported to cause birth defects or other problems in humans.

Breast-feeding Trimethoprim passes into the breast milk. However, this medicine has not been reported to cause serious problems in nursing babies.

Children This medicine has been used in a limited number of children 2 months of age or older, and tested in 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 may be more sensitive to the effects of trimethoprim. Blood problems may be more likely to occur in elderly 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 trimethoprim, it is especially important that your health care professional know if you are taking any of the following:

• Anticonvulsants (seizure medicine) or
• Methotrexate (e.g., Mexate) or
• Pyrimethamine (e.g., Daraprim) or
• Triamterene (e.g., Dyrenium) Use of these medicines with trimethoprim may increase the chance of side effects affecting the blood

• Anemia Patients with anemia may have an increased chance of side effects affecting the blood

• Kidney disease Patients with kidney disease may have an increased chance of side effects

• Liver disease Patients with liver disease may have an increased chance of side effects