Methyldopa and Carbidopa/Levodopa Interaction
Drug interaction information between Methyldopa and Carbidopa/Levodopa.
Methyldopa and Carbidopa/Levodopa have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Methyldopa and Carbidopa/Levodopa. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Both of these drugs are processed by the same enzyme in the body. Taking them together can cause the drugs to build up, which may lead to a fast heart rate or changes in blood pressure.
FDA Label Information
7.2 Drugs Metabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and bitolterol should be administered with caution in patients receiving entacapone regardless of the route of administration (including inhalation), as their interaction may result in increased heart rates, possibly arrhythmias, and excessive changes in blood pressure [ see Warnings and Precautions (5.10) ].
Methyldopa Also Interacts With
- Ferrous Sulfate moderate
- Tranylcypromine moderate
- Lithium minor
- Colestipol minor
- Enalapril minor
Carbidopa/Levodopa Also Interacts With
- Warfarin moderate
- Entacapone moderate
- Dobutamine moderate
- Dopamine moderate
- Epinephrine moderate
Frequently Asked Questions
What SPL severity band is on file for Methyldopa + Carbidopa/Levodopa?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Carbidopa/Levodopa has 13 labeled pairs on file vs Methyldopa's 7. In the moderate band specifically: Methyldopa has 3 (also Ferrous Sulfate, Tranylcypromine); Carbidopa/Levodopa has 8 (also Warfarin, Entacapone, Dobutamine, Dopamine).
What mechanism field is on file for Methyldopa and Carbidopa/Levodopa?
Both of these drugs are processed by the same enzyme in the body. Taking them together can cause the drugs to build up, which may lead to a fast heart rate or changes in blood pressure.
Carbidopa/Levodopa's labeled portfolio outnumbers Methyldopa
SPL source-record counts only. This page's band is moderate · classes on file: Methyldopa (Central Alpha-2 Agonist); Carbidopa/Levodopa (Dopamine Precursor Combination).
0 major · 3 moderate · 4 minor · 7 total
- Other moderate peers for Methyldopa
- Ferrous Sulfate
- Tranylcypromine
0 major · 8 moderate · 5 minor · 13 total
- Other moderate peers for Carbidopa/Levodopa
- Warfarin
- Entacapone
- Dobutamine
- Dopamine
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.