NutriStack
L-Tyrosine and Levodopa/Carbidopa, timing-sensitive.
L-tyrosine is a large neutral amino acid and can theoretically compete with levodopa for intestinal and blood-brain barrier transport when taken in large supplemental doses. A short trial of 1,000 mg/day tyrosine in people with Parkinson's disease receiving dopaminergic therapy was well tolerated, so the concern is mainly high-dose or poorly timed use. Taking tyrosine close to levodopa could still make motor response less predictable in protein-sensitive patients.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- L-Tyrosine and Levodopa/Carbidopa
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Emerging
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Timing Sensitive · Emerging evidence
Timing Sensitive
What is happening. L-tyrosine is a large neutral amino acid and can theoretically compete with levodopa for intestinal and blood-brain barrier transport when taken in large supplemental doses. A short trial of 1,000 mg/day tyrosine in people with Parkinson's disease receiving dopaminergic therapy was well tolerated, so the concern is mainly high-dose or poorly timed use. Taking tyrosine close to levodopa could still make motor response less predictable in protein-sensitive patients.
Mechanism. Levodopa and aromatic amino acids such as tyrosine use large neutral amino acid transport systems for gut absorption and brain entry. Competition at these transporters can reduce levodopa central availability, although low-dose tyrosine has not shown a clear clinical problem in limited human data.
Recommendation. Do not take L-tyrosine at the same time as levodopa/carbidopa. Separate high-dose tyrosine from levodopa by at least 2 hours, and stop the supplement if you notice more wearing off, delayed on, nausea, or dyskinesia. Keep your levodopa schedule consistent and tell your prescriber before using tyrosine daily.
Minimum separation. 120
Sources (2)
- Nutt JG, Woodward WR, Hammerstad JP, Carter JH, Anderson JL. The "on-off" phenomenon in Parkinson's disease. Relation to levodopa absorption and transport. N Engl J Med. 1984;310(8):483-488. PMID 6694694
- DiFrancisco-Donoghue J, Rabin E, Lamberg EM, Werner WG. Effects of Tyrosine on Parkinson's Disease: A Randomized, Double-Blind, Placebo-Controlled Trial. Mov Disord Clin Pract. 2014;1(4):348-353. PMID 30363894
Stack Score
How this pair moves the number.
Effect on the composite score
If both L-Tyrosine and Levodopa/Carbidopa are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.