Drug & supplement interaction

Tyrosine + Carbidopa, Levodopa

Carbidopa, Levodopa brand names: Sinemet CR, Sinemet, Rytary, Dhivy.

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

Tyrosine has a moderate interaction with Carbidopa, Levodopa. 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 Carbidopa, Levodopa

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

Moderate

LEVODOPA

Why this applies to Carbidopa, Levodopa

Carbidopa, Levodopa falls under LEVODOPA — the group Tyrosine interacts with.

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 about tyrosine and your Sinemet (carbidopa/levodopa): they may compete for the same doorway into your bloodstream. Levodopa is actually a building block your brain converts into dopamine, and it rides into your body on a transporter that also carries amino acids like tyrosine. If you take a tyrosine supplement around the same time, it could crowd out your levodopa, meaning less of it gets absorbed and reaches your brain.

In real life, that might show up as your Parkinson's symptoms (tremor, stiffness, slowness) not being as well controlled, or your dose seeming to wear off sooner. I'll be honest, this is based on how the two work on paper, not strong studies. To play it safe, separating them by at least 2 hours is reasonable. Please run it by your doctor or pharmacist before starting 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 Carbidopa, Levodopa 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. Carbidopa, Levodopa)
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 Carbidopa, Levodopa

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 Carbidopa, Levodopa, 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 Carbidopa, Levodopa

This page covers Tyrosine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carbidopa, Levodopa page lists 43 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 8 major · 24 moderate · 11 minor.

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

“Carbidopa/levodopa (Sinemet, Rytary) anchors Parkinson's treatment, and because symptom control hinges on how much levodopa actually reaches the brain, the 43 supplements and herbs on this list deserve real respect before you add any of them. Eight carry a major rating, and almost all of the serious entries weaken the drug rather than…”

Reviewed by 2 · Jul 18, 2026

Open the Carbidopa, Levodopa 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 Carbidopa, Levodopa 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 Carbidopa, Levodopa 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 Carbidopa, Levodopa
Top 5%

#76 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
Medication

About Levodopa and Carbidopa

What Is Levodopa and Carbidopa Used For?

Brand names: Sinemet CR, Sinemet, Rytary, Dhivy

Levodopa and carbidopa is used to treat Parkinson's disease, post-encephalitic parkinsonism (parkinsonism that develops after a brain infection), and symptomatic parkinsonism that can follow carbon monoxide or manganese poisoning. These indications are shared across the oral tablet, orally disintegrating tablet, extended-release tablet, and extended-release capsule formulations (including Sinemet, Rytary, Crexont, and generic products).

DUOPA — a carbidopa/levodopa suspension given through a tube directly into the small intestine — is specifically indicated for the treatment of motor fluctuations in patients with advanced Parkinson's disease. This is a product-specific indication and does not apply to the oral forms.

See full Levodopa and Carbidopa drug information
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 Carbidopa, Levodopa, 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 Carbidopa, Levodopa supplement interactions › Every supplement checked against Carbidopa, Levodopa, ranked by severity Levodopa and Carbidopa drug information › The full plain-English guide to this medication 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 Carbidopa, Levodopa Together: Common Questions

Can you take Tyrosine with Carbidopa, Levodopa?
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 Carbidopa, Levodopa 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 Carbidopa, Levodopa 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.