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Tiopronin is commonly used to prevent kidney stones in certain people with severe homozygous cystinuria, a condition that causes recurrent kidney stones. It works by reducing the amount of cystine in the urine, making kidney stones less likely to form. Common side effects include nausea, vomiting, diarrhea, joint pain, tiredness, and others. Tiopronin is available as a tablet that is swallowed.

Uses

What is tiopronin used for?

Tiopronin is commonly used to prevent kidney stones in certain people with severe homozygous cystinuria, an inherited condition that causes the formation of recurrent kidney stones.

Tiopronin may also be used for other conditions as determined by your health care provider.

How does tiopronin work (mechanism of action)?

High levels of an amino acid called cystine can lead to kidney stones. Tiopronin works by reducing the amount of cystine in the urine, making kidney stones less likely to form.

How is tiopronin supplied (dosage forms)?

Brands and other names

  • Thiola
  • Thiola EC

Dosage forms and strengths

  • 100 mg and 300 mg delayed-release oral tablets
  • 100 mg oral tablets

How should I store tiopronin?

Tiopronin should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of tiopronin?

The most common side effects of tiopronin are listed below. These side effects may vary depending on the tiopronin product used. Tell your health care provider if you have any of these side effects that bother you.

  • Nausea and vomiting
  • Diarrhea or soft stools
  • Ulcers (sores) in the mouth
  • Tiredness
  • Fever
  • Joint pain
  • Proteinuria (excess protein in the urine) (see below)
  • Stomach pain or bloating
  • Gas
  • Loss of appetite
  • Change in how things taste or smell
  • Skin problems such as rash, itching, hives, warts, or wrinkled skin

There may be other side effects of tiopronin that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of tiopronin?

While less common, the most serious side effects of tiopronin are described below, along with what to do if they happen.

Severe Allergic Reactions. Tiopronin may cause allergic reactions, which can be serious. Stop taking tiopronin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Proteinuria. Tiopronin can cause proteinuria, which means there is excess protein in the urine. This can lead to kidney problems. Your health care provider will monitor you before you start taking tiopronin, and regularly during treatment. Call your health care provider right away if you have any of the following symptoms of proteinuria. 

  • Urine (pee) that is foamy or bubbly
  • Peeing more often
  • Swelling in the hands, feet, face, and/or stomach
  • Shortness of breath
  • Tiredness
  • Loss of appetite
  • Upset stomach
  • Vomiting
  • Muscle cramps at night

Immune System Reactions. Tiopronin can cause inflammation of your liver, blood vessels, or lymph vessels and cause symptoms that look like a condition called lupus. Stop taking tiopronin and call your health care provider right away if you develop any of the following symptoms.

  • Rash
  • Joint pain
  • Fever
  • Weakness or unusual tiredness

Blood Disorders. Tiopronin can cause blood disorders, such as agranulocytosis, aplastic anemia, hemolytic anemia, low platelet levels (thrombocytopenia), and low white blood cell levels (leukopenia). Stop taking tiopronin and get help right away if you have any of the following symptoms of blood disorders.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infections
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Myasthenia Gravis. Tiopronin may cause myasthenia gravis, a condition that causes muscle weakness. It can also lead to myasthenic syndrome, which can cause your muscles to feel weak and tired. Stop taking tiopronin and call your health care provider right away if you have any of the following symptoms. 

  • Droopy eyelids
  • Changes in vision, such as double vision
  • Shortness of breath
  • Trouble walking, holding your head up, or using your arms and hands
  • Slurred speech
  • Hoarseness or weak voice
  • Trouble chewing or swallowing
  • A change in your facial expressions

Goodpasture Syndrome. Tiopronin may cause Goodpasture syndrome, a condition that happens when the body’s immune system attacks its own lungs and kidneys. Goodpasture syndrome can cause death if it is not treated quickly. Stop taking tiopronin and call your health care provider right away if you have any of the following symptoms. 

  • Tiredness
  • Nausea and vomiting
  • Trouble breathing
  • Pale skin
  • Peeing less
  • Blood in the urine
  • Foamy urine
  • Burning or stinging when you pee, or difficulty peeing
  • Pain in your back, below the ribs
  • Swelling of the legs, feet, and/or hands
  • High blood pressure

Pemphigus. Tiopronin may cause pemphigus, a condition that happens when the body’s immune system attacks its own skin and mucus membranes. Pemphigus may require steroid treatment. Stop taking tiopronin and call your health care provider right away if you develop blisters in your eyes, nose, mouth, throat, or genitals.

Warnings & Precautions

Who should not use tiopronin?

Allergies to Ingredients. People who are allergic to any of the following should not take tiopronin.

  • Thiola
  • Thiola EC
  • Tiopronin
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific tiopronin products they stock.

Blood Disorders When Previously Taking Tiopronin. Tiopronin should not be restarted if you have a history of developing blood disorders, such as agranulocytosis, aplastic anemia, or thrombocytopenia, while taking tiopronin. 

Pregnancy. Tiopronin should not be used during pregnancy, except in certain severe cases where the health care provider determines that the benefits outweigh the risks. If you become pregnant while taking tiopronin, contact your health care provider right away. See the Pregnancy section for more details.

Breastfeeding. Do not take tiopronin if you are breastfeeding. You must either stop breastfeeding or stop taking tiopronin. See the Breastfeeding section for more details.

What should I know about tiopronin before using it?

Do not take tiopronin unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share tiopronin with other people, even if they have the same condition as you. It may harm them.

Keep tiopronin out of the reach of children.

Follow your health care provider’s recommendations regarding dietary instructions, fluid intake, and the use of alkali to help manage your condition. Your health care provider may suggest that you drink fluids when you wake up at night to urinate, before returning to bed. They will also guide you on when to drink extra fluids, such as during heavy sweating.

Your health care provider will monitor you regularly while you are taking tiopronin. Keep all appointments for follow-up and lab tests.

Tiopronin may affect your skin, especially with long-term use. This is thought to be caused by tiopronin’s effect on collagen. You may notice your skin becoming wrinkled and/or fragile. Notify your health care provider if this happens.

Tiopronin may cause fevers, especially during the first month of treatment. If this happens, call your health care provider right away. They may tell you to temporarily stop taking tiopronin until your fever goes away, and then restart the medicine at a lower dose.

Tiopronin may cause an itchy rash. If you get a rash, call your health care provider. You may need to temporarily stop taking tiopronin and start again at a lower dose.

Tiopronin may affect your sense of taste and/or smell. This is not harmful, but if you develop this side effect and it bothers you, call your health care provider.

People who are 65 and older can be at greater risk for some side effects from tiopronin. Talk to your health care provider about your risks if you are in this age group.

If you are taking delayed-release tiopronin, swallow the tablet whole. If you cannot do so, you can crush the tablet and mix it with applesauce. To do this, crush the tablet in a clean, dry pill crusher, or use a mortar and pestle. Only crush one tablet at a time. Put the crushed tablet into a clean container, and add one tablespoon of applesauce. Mix the applesauce and crushed tablet together and swallow the mixture right away. Then, add some tap water to the same container, mix, and drink the water. This ensures that all of the medicine is taken. If you cannot take the medicine right away, you can store the mixture in a refrigerator for up to two hours. If you put the mixture in a refrigerator, take special precautions to keep it away from children who also use the refrigerator. Throw away any mixture that has not been taken within two hours.

What should I tell my health care provider before using tiopronin?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if tiopronin is right for you.

In particular, make sure that you discuss any of the following.

Previous D-Penicillamine Use. Tell your health care provider if you have previously taken the medicine d-penicillamine (Cuprimine or Depen), which is a medicine used for certain types of kidney stones and other conditions. Tell your health care provider if you have had any side effects or reactions to d-penicillamine.

Current and Past Health Conditions. Tell your health care provider if you have or have had any of the following.

  • Kidney or liver problems
  • Lupus, Goodpasture syndrome, or any other autoimmune conditions
  • Myasthenia gravis
  • Blood disorders, such as agranulocytosis, aplastic anemia, or thrombocytopenia

Pregnancy. Tiopronin is not typically used during pregnancy, except in severe cases when the health care provider thinks that the benefits outweigh the risks. It is not known if or how tiopronin could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant. If you are taking tiopronin and become pregnant, call your health care provider right away. 

Breastfeeding. Tiopronin may pass into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will advise you if you should stop breastfeeding or stop tiopronin.

Interactions

Does tiopronin interact with foods or drinks?

If you are taking immediate-release tiopronin, take it at least one hour before or two hours after meals if possible. It is unknown if drinking alcohol will affect immediate-release tiopronin.

Delayed-release tiopronin can be taken with or without food. Take it the same way each time (always with food, or always without food). Drinking alcohol can cause delayed-release tiopronin to be released too fast. Do not drink alcohol two hours before or three hours after taking delayed-release tiopronin.

If you are not sure which tiopronin product you take, ask your health care provider or pharmacist. 

Does tiopronin interact with other medicines (drug interactions)?

There are no known interactions between tiopronin and other medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much tiopronin?

If you or someone else has used too much tiopronin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of tiopronin?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.