Ornithine is an amino acid that is made in the body. It's not used to create protein, but plays a role in other processes. It can also be made in a lab.

Ornithine might help to increase levels of another amino acid called arginine. It might also increase levels of hormones that increase muscle size.

People use ornithine for athletic performance, dry skin, insomnia, wound healing, and other purposes, but there is no good scientific evidence to support most of these uses.

Don't confuse ornithine with ornithine alpha-ketoglutarate (OKG) or L-Ornithine-L-Aspartate. These are not the same.
When taken by mouth: Ornithine is possibly safe when used at doses up to 500 mg daily for up to 8 weeks.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if ornithine is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.


Natural Medicines rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
  • Athletic performance. Taking ornithine by mouth might reduce fatigue and improve some measures of athletic performance.
There is interest in using ornithine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
Insufficient evidence Effectiveness definitions

Dosing & administration

There isn't enough reliable information to know what an appropriate dose of ornithine might be. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult a healthcare professional before using.

Interactions with pharmaceuticals

It is not known if Ornithine interacts with any medicines. Before taking Ornithine, talk with your healthcare professional if you take any medications.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods.
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This monograph was last reviewed on 25/05/2022 21:35:51 and last updated on 25/09/2022 05:40:14. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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