Can You Take L-Arginine and Ornithine HCl Together?

Dose or timing may matter

The short answer

Ornithine is part of the urea cycle and converts to arginine in vivo. Supplementing both provides dual-source arginine loading, potentially leading to excessive nitric oxide production and gastrointestinal distress at high doses.

How to arrange timing

Keep combined doses moderate. If taking both for NO support, reduce the dose of each proportionally.

Reference

Reference noted for this combination: Cynober L. Ornithine alpha-ketoglutarate as a potent precursor of arginine and nitric oxide: a new job for an old friend. J Nutr. 2004;134(10 Suppl):2858S-2862S

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.