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Tiopronin (By mouth)

Tiopronin (tye-oh-PROE-nin)

Prevents kidney stones.

Brand Name(s):

Thiola, Thiola EC

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to tiopronin or if you are breastfeeding.

How to Use This Medicine:

Tablet, Delayed Release Tablet

  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
  • Swallow the delayed-release tablet whole. Do not crush, break, or chew it.
  • Take the tablet at least 1 hour before or 2 hours after meals.
  • Drink extra fluids so you will urinate more often and help prevent kidney problems.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not drink alcohol 2 hours before and 3 hours after using Thiola® EC.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant, or if you have kidney disease, or a history of severe toxicity to d-penicillamine.
  • Do not breastfeed during treatment with this medicine.
  • This medicine may cause kidney problems.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Bloody or cloudy urine, change in how much or how often you urinate, difficult or painful urination
  • Dizziness, lightheadedness, or fainting
  • Swelling of the face, feet, or lower legs

If you notice these less serious side effects, talk with your doctor:

  • Change in or loss of taste
  • Joint or muscle pain
  • Nausea, vomiting, diarrhea, loss of appetite, weight loss
  • Wrinkled skin

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088


Last Updated: 5/1/2020

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