Generic Name: Trimethoprim

  • What is Primsol?

    Primsol is a liquid antibiotic prescribed to treat acute ear infections in children >6 months old and uncomplicated urinary tract infections in adults.

  • What is the most important information I should know about Primsol?

    Primsol can cause a serious blood disorder, especially if taken in high doses or for a long period of time. This condition requires prompt medical treatment. Notify your doctor immediately if you develop fever, pale skin, sore throat, or small red or purple spots on the skin. Your doctor may order blood tests to monitor your health while taking Primsol.

    Primsol should not be used for the prevention or long-term treatment of ear infections or urinary tract infections.

    Use Primsol with caution if you have a blood or bone marrow disorder, liver or kidney disease, or you have ever had vitamin deficiencies. Primsol interferes with your body's ability to absorb folic acid, an important B vitamin. Your doctor may have you take extra vitamins during treatment with Primsol.

    Primsol should not be given to infants <2 months of age.

  • Who should not take Primsol?

    Do not take Primsol if you have an allergic reaction to it or to other drugs that contain trimethoprim.

    Do not take Primsol if you have been diagnosed with megaloblastic (pernicious) anemia, a blood cell disorder caused by a B vitamin deficiency.

  • What should I tell my doctor before I take the first dose of Primsol?

    Tell your doctor about all prescription, over-the-counter, and herbal medications you are taking before beginning treatment with this drug. Also, talk to your doctor about your complete medical history, especially if you have liver or kidney disease, vitamin deficiencies, or a blood disorder. Also, tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.

  • What is the usual dosage?

    The information below is based on the dosage guidelines your doctor uses. Depending on your condition and medical history, your doctor may prescribe a different regimen. Do not change the dosage or stop taking your medication without your doctor's approval.

    Adults: The usual adult dose is 100 milligrams (mg) (10 milliliters [mL] or 2 teaspoons) taken every 12 hours, or 200 mg (20 mL or 4 teaspoons) taken every 24 hours, each for 10 days. For adults with impaired kidney function, the recommended dose of Primsol will be half the usual dose.

    Children: For children ≥6 months and older, the recommended dose is 10 milligrams per 2.2 pounds of body weight per 24 hours, given in divided doses every 12 hours for 10 days. Follow the directions that come with the prescription carefully and if you have questions, call your doctor or pharmacy. For children with impaired kidney function, the recommended dose of Primsol will be half the usual dose.

  • How should I take Primsol?

    Primsol liquid is taken by mouth with or without food, twice daily, 12 hours apart. When Primsol is prescribed in just one daily dose, take it at about the same time each day.

  • What should I avoid while taking Primsol?

    Avoid becoming pregnant or breastfeeding while using Primsol.

  • What are possible food and drug interactions associated with Primsol?

    When Primsol is used with certain other drugs, the effects of either drug could be increased, decreased, or altered. It is especially important to check with your doctor before combining Primsol with methotrexate or phenytoin.

  • What are the possible side effects of Primsol?

    Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking this drug.

    Side effects may include: diarrhea, vomiting, skin rash, abdominal pain

  • Can I receive Primsol if I am pregnant or breastfeeding?

    Primsol can interfere with the absorption of important vitamins that are vital to your baby's development during pregnancy. It is not recommended for pregnant women unless your doctor determines the benefit to your health outweighs the risk to your unborn baby. Tell your doctor immediately if you are pregnant or plan to become pregnant while taking Primsol. Primsol appears in breast milk and can harm your nursing infant. Your doctor may advise you to stop breastfeeding if Primsol is essential to your health.

  • What should I do if I miss a dose of Primsol?

    Take the forgotten dose as soon as you remember. However, if it is almost time for your next dose, skip the one you missed and return to your regular schedule. Do not take two doses at once.

  • How should I store Primsol?

    Store at room temperature away from light.

Meet the Pharmacists

I'm Kristen Dore, PharmD. Welcome to PDR Health!

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