What the FDA labels say about taking them together
Levodopa and risperidone
Levodopa's FDA label of July 20, 2026 names risperidone in its drug interactions section, and risperidone's label names levodopa too. The levodopa label: “Antagonists and Isoniazid Dopamine D2 receptor antagonists and isoniazid may reduce the effectiveness of levodopa. Monitor patients for worsening Parkinson's symptoms.”
Check it at the source: the levodopa FDA label on DailyMed (effective July 20, 2026, Merz Pharmaceuticals, LLC); the risperidone FDA label on DailyMed (effective May 28, 2026, Janssen Pharmaceuticals, Inc.).
What does the levodopa label say about risperidone?
Levodopa label, drug interactionsAntagonists and Isoniazid Dopamine D2 receptor antagonists (e.g., phenothiazines, butyrophenones, risperidone, metoclopramide) and isoniazid may reduce the effectiveness of levodopa. Monitor patients for worsening Parkinson's symptoms.
Source: FDA drug label (Inbrija), Merz Pharmaceuticals, LLC, effective July 20, 2026 (SPL set 077c0f39-a3a2-4b2b-a184-09131889dcfb), via openFDA; the full label on DailyMed
What does the risperidone label say about levodopa?
Risperidone label, drug interactionsLevodopa and Dopamine Agonists RISPERDAL may antagonize the effects of levodopa and dopamine agonists.
Risperdal Consta label (Janssen Pharmaceuticals, Inc., November 5, 2025), drug interactionsAvoid alcohol. ( 7.1 ) Due to hypotensive effects, hypotensive effects of other drugs with this potential may be enhanced. ( 7.2 ) Effects of levodopa and dopamine agonists may be antagonized. ( 7.3 ) Cimetidine and ranitidine increase the bioavailability of risperidone. ( 7.5 ) Clozapine may decrease clearance of risperidone. ( 7.7 ) Fluoxetine and paroxetine increase plasma concentrations of risperidone. ( 7.12 ) Carbamazepine and other enzyme inducers decrease plasma concentrations of risperidone.
Rykindo Extended-Release Microspheres label (Shandong Luye Pharmaceutical Co., Ltd., May 26, 2026), drug interactionsDopamine Agonists Clinical Impact RYKINDO may antagonize the effects of levodopa and dopamine agonists. Intervention Caution should be used when RYKINDO is administered in combination with levodopa and dopamine agonists.
Source: FDA drug label (Risperdal Consta, NDA021346), Janssen Pharmaceuticals, Inc., effective November 5, 2025 (SPL set bb34ee82-d2c2-43b8-ba21-2825c0954691), via openFDA
Source: FDA drug label (Rykindo Extended-Release Microspheres, NDA212849), Shandong Luye Pharmaceutical Co., Ltd., effective May 26, 2026 (SPL set 58534c96-96f5-4c2e-a061-92d4506aee91), via openFDA
Source: FDA drug label (Risperidone, NDA020588), Janssen Pharmaceuticals, Inc., effective August 20, 2026 (SPL set 701e1cd8-2868-4d29-85a9-a2212c88165f), via openFDA
Source: FDA drug label (RISPERDAL), Janssen Pharmaceuticals, Inc., effective May 28, 2026 (SPL set 7e117c7e-02fc-4343-92a1-230061dfc5e0), 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
| Levodopa | Risperidone | |
|---|---|---|
| Labeled for | Parkinson's disease | Bipolar disorder, Schizophrenia |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.0368 per tablet 0.25 mg tablet |
| 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