What the FDA labels say about taking them together
Carbidopa and tolcapone
Tolcapone's FDA label of October 2, 2020 names carbidopa in its boxed warning section; the carbidopa label PlainMeds reads does not name tolcapone. The tolcapone label: “… should ordinarily be used in patients with Parkinson's disease on l-dopa/carbidopa who are experiencing symptom fluctuations and are not responding satisfactorily to or are not appropriate candidates for other …”
Check it at the source: the carbidopa FDA label on DailyMed (effective July 2, 2020, Oceanside Pharmaceuticals); the tolcapone FDA label on DailyMed (effective October 2, 2020, Bausch Health US LLC).
What does the carbidopa label say about tolcapone?
Carbidopa's label (effective July 2, 2020) does not name tolcapone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Carbidopa), NDA017830 (Aton), as published by Oceanside Pharmaceuticals, effective July 2, 2020 (SPL set d5204e5e-10ef-4758-8fc6-cb710048c687), via openFDA; the full label on DailyMed
What does the tolcapone label say about carbidopa?
Tolcapone label, boxed warningWARNING Because of the risk of potentially fatal, acute fulminant liver failure, TASMAR (tolcapone) should ordinarily be used in patients with Parkinson's disease on l-dopa/carbidopa who are experiencing symptom fluctuations and are not responding satisfactorily to or are not appropriate candidates for other adjunctive therapies (see INDICATIONS and DOSAGE AND ADMINISTRATION sections).
Tolcapone label, drug interactionsHowever, no effects were seen on the pharmacokinetics of the COMT substrate carbidopa.
Source: FDA drug label (Tasmar), Bausch Health US LLC, effective October 2, 2020 (SPL set a0e47a9d-78e7-4523-983a-aa259f221736), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Carbidopa | Tolcapone | |
|---|---|---|
| Labeled for | Parkinson's disease | Parkinson's disease |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.536 per tablet 25 mg tablet | n/a |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once