What is it used for?
Helps to decrease cognitive fatigue due to physically stressful situations (e.g. extended wakefulness, exposure to cold, excessive noise) (Mahoney et al. 2007; O'Brien et al. 2006; Magill et al. 2003; Thomas et al. 1999; Dollins et al. 1995; Neri et al. 1995).
Who does this guide cover?
Adults 18 years and older
How is it taken?
Oral
Which forms are covered?
this reference excludes foods or food-like dosage forms as indicated in the Compendium of references Guidance Document.
Quantities
10 - 20 grams of L-Tyrosine, per day; Not to exceed 10 grams per single dose (Mahoney et al. 2007; O'Brien et al. 2006; Magill et al. 2003; Thomas et al. 1999; Neri et al. 1995).
How is it used?
Take up to 1 hour before, or during periods of physical stress (Mahoney et al. 2007; O'Brien et al. 2006; Magill et al. 2003; Thomas et al. 1999; Neri et al. 1995).
How long is it used?
For occasional use only.
Warnings and precautions
Ask a healthcare professional before use if you are pregnant or breastfeeding.
When should it be avoided?
The reference does not require an additional label statement in this section. This does not establish an absence of risk.
Possible side effects
The reference does not require an additional label statement in this section. This does not establish an absence of risk.
Storage
Must be established in accordance with the requirements described in the applicable product regulations.
Preparation details
Ingredient identity, preparation requirements, and other details that define the scope of this guide.
Ingredients and preparations
| Proper name(s) | Common name(s) | Source information / Source ingredient(s) |
|---|---|---|
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|
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References: Proper names: source ingredient database 2026; NIH 2024; USP-NF 2024; Common names: NIH 2024; USP-NF 2024; Source information: source ingredient database 2026.
Other ingredients
Must be chosen from the current source ingredient database and must meet the limitations outlined in the database.
Preparation and quality requirements
The finished product specifications must be established in accordance with the requirements described in the source authority source’s product quality guidance.
The active ingredient must comply with the requirements outlined in the source ingredient database.
Guide change history
Updates to this SupplementSafety.org guide.
Minor updates
Updated guide wording, organization, and source presentation. Added our editorial change history.
Initial release
Initial SupplementSafety.org guide prepared from source reference material.
Validation: Not yet completed. Editorial updates do not constitute clinical validation.
Sources
Source information
This guide organizes source material about uses, preparations, amounts, and precautions. Read the conditions alongside each statement; the information may apply only to particular preparations or populations.
The source document includes supporting references. We have not independently summarized or assessed every cited study for this guide.
- Source document version
- January 30, 2026
- Source captured
- Aug 15, 2026
- Editorial work
- Editorial preparation. Independent clinical review has not been recorded for this guide.
Full citations are available through the link above. Verification is required to open them; reading this guide does not require verification.
Taking a medication too?
Explore our supplement–medication interaction checker. Its coverage and review status are shown with the results; a missing finding does not establish that a combination is safe.