Drug & supplement interaction

Tyrosine + Levodopa, Carbidopa

Levodopa, Carbidopa brand name: Duodopa.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Tyrosine has a moderate interaction with Levodopa, Carbidopa. Theoretically, tyrosine might decrease the effectiveness of levodopa.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Tyrosine and Levodopa, Carbidopa

Here is the interaction we found between these two, with the evidence behind it.

Moderate

LEVODOPA

Theoretically, tyrosine might decrease the effectiveness of levodopa.
Tyrosine and levodopa compete for absorption in the proximal duodenum by the large neutral amino acid (LNAA) transport system. Advise patients to separate doses of tyrosine and levodopa by at least 2 hours.
Severity Moderate Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know about your levodopa/carbidopa (Duodopa): both levodopa and the amino acid tyrosine hitch a ride into your body through the same doorway in your small intestine, called the large neutral amino acid transporter. If you take a tyrosine supplement around the same time as your dose, they can crowd each other out, and less levodopa may get absorbed.

For Parkinson's, that could mean your medicine feels weaker, with more stiffness, slowness, or tremor creeping back, or shorter "on" time between doses. This is based on how the drugs work, not strong human studies, so it's more of a precaution. A simple fix is spacing them out by at least 2 hours. Please check with your doctor or pharmacist before adding tyrosine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. DiPiro JT, Talbert RL, Yee GC, et al; eds. Pharmacotherapy: A pathophysiologic approach. 4th ed. Stamford, CT: Appleton & Lange, 1999.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Tyrosine Also Interacts With Other Medications

Tyrosine has 20 moderate known drug interactions in our database — the Levodopa, Carbidopa one above is one of them. If you take anything else, check it against the full list below.

Moderate 20 No known interaction 2,810 (incl. Levodopa, Carbidopa)
Taking anything else?

Check Another of Your Medications Against Tyrosine

Covers the 2,830 medications we’ve checked against Tyrosine. Pick one to open its full report.

From our Q&A

Questions About Tyrosine or Levodopa, Carbidopa

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Tyrosine or Levodopa, Carbidopa, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Levodopa, Carbidopa

This page covers Tyrosine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levodopa, Carbidopa page lists 26 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Branched-chain Amino Acids (bcaa) (major), Cowhage (major), Indian Snakeroot (major), Magnesium (major) and Phenylalanine (major).

By severity: 7 major · 17 moderate · 2 minor.

From our pharmacist’s overview on the Levodopa, Carbidopa page

“Cowhage is the first thing to know here. It naturally contains levodopa, sometimes 75 to 400 mg per dose, so stacking it on Levodopa, Carbidopa (Duodopa) risks levodopa excess.”

Reviewed by 2 · Jul 18, 2026

Open the Levodopa, Carbidopa interaction page

One more smart check

Taking Tyrosine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 4,448 real supplement products containing Tyrosine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Tyrosine. Your product may carry other ingredients that interact with Levodopa, Carbidopa too, on top of Tyrosine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Tyrosine and Levodopa, Carbidopa Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Tyrosine
Top 5%

#41 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Levodopa, Carbidopa
Top 25%

#426 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Tyrosine

What is Tyrosine?

  • Mental focus and alertness
  • Coping with stress
  • Fatigue and sleep loss
  • Mood support
  • Athletic and cognitive performance

L-tyrosine is an amino acid your body uses to make brain chemicals like dopamine and norepinephrine. Some studies suggest it may help mental performance during short-term stress, sleep loss, or cold, but the evidence is mixed and it is not proven for everyday focus or mood. It is generally well tolerated in healthy adults, but check with your pharmacist or doctor before using it, especially during pregnancy or if you have a thyroid condition.

Read the full Tyrosine monograph & all interactions
Keep checking

Other Drugs & Tyrosine

Browse every other medication we’ve checked against Tyrosine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
20Moderate
0Minor
2,809No known interaction
20 Moderate 2,809 No interaction
Moderate

20 interactions

No interaction 2,809 drugs checked — show the list

We also checked Tyrosine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,809 medications checked with no known interaction — see the full Tyrosine list.

See the full Tyrosine interactions page
See every supplement checked against Levodopa, Carbidopa, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Tyrosine monograph › Uses, safety, and every drug interaction in one place Levodopa, Carbidopa supplement interactions › Every supplement checked against Levodopa, Carbidopa, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Tyrosine and Levodopa, Carbidopa Together: Common Questions

Can you take Tyrosine with Levodopa, Carbidopa?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Tyrosine and Levodopa, Carbidopa interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Levodopa, Carbidopa and Tyrosine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.