L-Arginine Hydrochloride vs. L-Arginine Pyroglutamate

Among 1,304 on-market l-arginine products with an identifiable primary form, 43.2% use L-Arginine Hydrochloride (563 products) and 4% use L-Arginine Pyroglutamate (52).

	L-Arginine Hydrochloride	L-Arginine Pyroglutamate
Quality tier	Unrated	Unrated
L-Arginine by weight	82.7%	57.4%
Share of market	43.2%	4%
On-market products	563	52
Median declared dose	413.5 mg middle half: 84.35–827	574 mg middle half: 354.15–861
Most common brands	Source Naturals, Vitamin World, Best Naturals	Source Naturals, Anabolic Warfare, Higher Nature

Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).

Why L-Arginine Hydrochloride is unrated

Largest disclosed salt form; no human head-to-head bioavailability study of arginine HCl vs free arginine or other salts was located. The best-supported finding on arginine delivery is that oral citrulline raises plasma arginine more effectively than oral arginine itself (a separate compound).

Source: Schwedhelm E et al. 2008, Br J Clin Pharmacol 65(1):51-9, PMID 17662090 (citrulline vs arginine, not salt forms)

Why L-Arginine Pyroglutamate is unrated

No head-to-head human bioavailability or efficacy comparison of this form was located in PubMed searches.

Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology). This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.

L-Arginine Hydrochloride vs. L-Arginine Pyroglutamate

Why L-Arginine Hydrochloride is unrated

Why L-Arginine Pyroglutamate is unrated

Other l-arginine comparisons