Tiopronin: uses, dosing, side effects & brands
Tiopronin is a reducing and complexing thiol sold in the U.S. under 3 brand and generic names. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Reducing and Complexing Thiol
- Available as
- Tablet, delayed release · Tablet
- Sold as
- 3 products — Thiola Ec, Thiola and Tiocystin
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How Thiola Ec is dosed
From the FDA label for Thiola Ec (application NDA211843). Other tiopronin products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
2.1 Recommended Dosage Adults: The recommended initial dosage in adult patients is 800 mg/day. In clinical studies, the average dosage was about 1,000 mg/day. Pediatrics: The recommended initial dosage in pediatric patients weighing 20 kg and greater is 15 mg/kg/day. Avoid dosages greater than 50 mg/kg per day in pediatric patients [see Warnings and Precautions (5.1), Use in Specific Populations (8.4)]. Administer Tiopronin Delayed-Release Tablets in 3 divided doses at the same times each day, with or without food. Maintain a routine pattern with regard to meals. Consider starting Tiopronin Delayed-Release Tablets at a lower dosage in patients with history of severe toxicity to d-penicillamine. 2.2 Preparation and Administration Instructions For patients who cannot swallow the tablet whole, Tiopronin Delayed-Release Tablets can be crushed and mixed with applesauce. Administration of Tiopronin Delayed-Release Tablets with other liquids or foods has not been studied and is not recommended. Preparation and Administration of Tiopronin Delayed-Release Tablets Mixed in Applesauce For patients who can swallow semi-solid food, Tiopronin Delayed-Release Tablets can be crushed and mixed with applesauce: 1. Crush the Tiopronin Delayed-Release Tablet in a clean pill crusher or mortar and pestle. Always crush one tablet at a time. 2. Measure approximately one tablespoon of applesauce and…
Everything below is the FDA label for Thiola Ec (tablet, delayed release). Tiopronin is also sold as tablet, and those are different medicines to take — follow the label for the one you were prescribed.
Thiola Ec side effects
The following adverse reactions are discussed in greater detail in other sections of the labeling: • Proteinuria [see Warnings and Precautions (5.1)] • Hypersensitivity [see Warnings and Precautions (5.2)] Most common adverse reactions (≥10%) are nausea, diarrhea or soft stools, oral ulcers, rash, fatigue, fever, arthralgia, proteinuria, and emesis. (6) To report SUSPECTED ADVERSE REACTIONS, contact BioComp Pharma, Inc. at toll-free phone # 1-866- 762-2365 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed in the clinical trials of the drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse reactions occurring at an incidence of ≥5% in an uncontrolled trial in 66 patients with cystinuria age 9 to 68 years are shown in the table below. Patients in group 1 had previously been treated with d-penicillamine; those in group 2 had not. Of those patients who had stopped taking d-penicillamine due to toxicity (34 out of 49 patients in group 1), 22 were able to continue treatment with Tiopronin Tablets. In those without prior history of d-penicillamine treatment, 6% developed reactions of sufficient severity to require Tiopronin Tablets withdrawal. Table 1 presents…
Who shouldn’t take Thiola Ec
Tiopronin Delayed-Release Tablets are contraindicated in patients with hypersensitivity to tiopronin or any other components of Tiopronin Delayed-Release Tablets [see Warnings and Precautions (5.2)]. Hypersensitivity to tiopronin or any component of Tiopronin Delayed-Release Tablets (4)
Thiola Ec drug interactions
7.1 Alcohol Tiopronin is released faster from Tiopronin Delayed-Release Tablets in the presence of alcohol and the risk for adverse events associated with Tiopronin Delayed-Release Tablets when taken with alcohol is unknown. Avoid alcohol consumption 2 hours before and 3 hours after taking Tiopronin Delayed-Release Tablets [see Clinical Pharmacology (12.3)].
Every tiopronin product we track (3)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 70/100 | Prescription | Tablet | No data | — | View → | |
| 2 | Not yet rated | Prescription | Tablet | No data | — | View → | |
| 3 | Not yet rated | Prescription | Tablet | No data | — | View → |
What tiopronin pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| 1A | 100 mg | white | round | — |
| 3A | 300 mg | white | round | — |
| T3 | 300 mg | white | round | — |
| T1 | 100 mg | white | round | — |
| L6 | 300 mg | white | round | — |
| M | 100 mg | white | round | — |
Can you crush or split tiopronin?
The tiopronin labels that address it permit crushing or splitting in the terms they state — quoted per product, because the instruction belongs to the form.
What each tiopronin label says about crushing, splitting and chewingHow long tiopronin keeps
The date on a sealed pack is not the only one: some tiopronin labels start a second clock once the product is opened or mixed, as short as 2 hours.
Does tiopronin expire? The in-use limits and storage rules from its labelsWhat people report to the FDA about tiopronin
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 251 reports naming tiopronin, and the FDA flagged 83% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- pyrexia15 reports
- nausea14 reports
- vomiting14 reports
- nephrotic syndrome13 reports
- diarrhoea12 reports
- pneumonia12 reports
- tubulointerstitial nephritis12 reports
- alanine aminotransferase increased9 reports
Read these as a signal, not a rate. A report does not mean tiopronin caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 26, 2026.
Related calculators
Frequently asked questions
What is Thiola Ec?
Thiola Ec (Tiopronin) is a reducing and complexing thiol.
What kind of drug is tiopronin?
The FDA classifies tiopronin as a reducing and complexing thiol. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take tiopronin with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run tiopronin against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is tiopronin sold under?
We track 3 tiopronin-containing products in the U.S.: Thiola Ec, Thiola and Tiocystin. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does tiopronin come in?
Across the brands we track, tiopronin is currently marketed as tablet, delayed release and tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic tiopronin?
We do not currently list a generic-labelled tiopronin product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Tiopronin: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/tiopronin
- MLA
- “Tiopronin: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/tiopronin.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for tiopronin on DailyMed (NIH) ↗.