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L-Tryptophan Safety: History, Drug Interactions and the Label Dose
L-tryptophan safety turns on its history and its drug interactions. A 1989 outbreak of eosinophilia-myalgia syndrome was linked to manufactured L-tryptophan, and it should not be mixed with some medicines without advice. In Glyco Defender it is the 20th blend line, so a dropperful holds at most 0.77 mg.
Written by the Glyco Defender label deskUpdated · 4 min read
Is L-tryptophan safe to take?
It depends on the product and on what else you take. In 1989, an outbreak of eosinophilia-myalgia syndrome was linked to manufactured L-tryptophan supplements.
More than 1,500 people were affected, and 37 deaths were attributed to it. FDA issued a nationwide warning and recall, and nearly all cases traced to one manufacturer's products (NORD, Eosinophilia-Myalgia Syndrome).
That is history, not a verdict on every bottle today. It does explain why the ingredient draws careful reading.
What medicines clash with L-tryptophan?
Several. It should not be used without medical advice with MAO inhibitors, tramadol, dextromethorphan, meperidine or sedatives (Drugs.com, L-tryptophan).
The same caution covers other serotonin-raising supplements such as 5-HTP and St. John's wort. It is also considered likely unsafe in pregnancy (Drugs.com, L-tryptophan).
| Situation | Advice |
|---|---|
| MAO inhibitors, tramadol, meperidine | Not without medical advice (Drugs.com, L-tryptophan) |
| Dextromethorphan, sedatives | Not without medical advice (Drugs.com, L-tryptophan) |
| 5-HTP, St. John's wort | Avoid combining (Drugs.com, L-tryptophan) |
| Pregnancy | Considered likely unsafe (Drugs.com, L-tryptophan) |
Do not stop an antidepressant or pain medicine because of a supplement. Ask your prescriber first.
How much L-tryptophan is in Glyco Defender?
At most 0.77 mg per dropperful. It is the 20th of 21 blend lines, so it cannot weigh more than 15.47 divided by 20.
That is less than one thousandth of a gram. The real figure is not printed, which blend rules allow (21 CFR 101.36 (eCFR)). The label also bars use in pregnancy and by anyone under 18.
A tiny share lowers the chance of a strong effect, but it does not erase a drug-interaction rule. If you take any medicine listed above, bring the label to your pharmacist.
Glyco Defender: from $49 a bottle30 mL · 1, 3 or 6 bottles · free US shipping on 6 · 60-day money-back guarantee
See packsWhat should you check before using these drops?
Check your medicine list against the label, and ask a clinician when in doubt.
The fit check covers five questions, and the side effects page lists the other cautions.
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FAQ01
Questions about L-tryptophan
What was the 1989 L-tryptophan outbreak?
It was an outbreak of eosinophilia-myalgia syndrome linked to manufactured L-tryptophan supplements (NORD, Eosinophilia-Myalgia Syndrome). FDA issued a nationwide warning and recall in November 1989.
Can I take L-tryptophan with an antidepressant?
Not without advice. L-tryptophan raises serotonin, and combining it with some serotonin-affecting medicines is cautioned against (Drugs.com, L-tryptophan). Ask your prescriber before using a product that lists it.
Where is L-tryptophan on the Glyco Defender label?
It is the 20th of 21 blend lines, just ahead of L-carnitine HCl. Only the total blend weight, 15.47 mg, is printed, not its own amount.
Who wrote this02
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, CDC, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is run by a licensed U.S. retail desk for Glyco Defender, not by the manufacturer or the label's distributor. Buying through our order links earns us money.
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