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Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction

Luigi Cormio, Mario De Siati, Fabrizio Lorusso, Oscar Selvaggio, Lucia Mirabella, Francesca Sanguedolce, Giuseppe Carrieri

Urology 2011 77(1):119–122

Bibliography

PubMed: PMID 21195829
DOI: 10.1016/j.urology.2010.08.028
Funding: Not yet independently verified in full text
Competing interests: Not yet independently verified in full text

Study snapshot

Design	Single-blind pilot intervention with sequential one-month placebo and L-citrulline periods
Model	Men with mild erectile dysfunction
Sample	24 men completed
Intervention	Placebo for one month followed by 1.5 g/day L-citrulline for one month
Duration	Two sequential one-month phases
Endpoints	Erection hardness score; Intercourse frequency; Treatment satisfaction; Adverse events

What the study showed, in plain terms

A small 2011 pilot found higher erection-hardness scores during citrulline use than during a preceding placebo month in men with mild erectile dysfunction.

Key findings

Twelve of 24 men reached a normal erection-hardness score during citrulline compared with two during placebo.

What this study can and cannot tell us

Only 24 participants, fixed placebo-before-treatment order, single blinding, no comparison with optimized standard treatment; does not establish efficacy of a proprietary nitric oxide product.

Citation network

Articles citing this research paper

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Biohack Blueprint analyses that reference this study in their evidence base.

Sep 27, 2026 Nitric Oxide and Erectile Dysfunction: Supplements vs TreatmentsNitric oxide and ED explained: vascular signaling, arginine and citrulline trials, prescription treatments, medication risks and limits of Nitralis evidence.Read analysis

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified 27 September 2026

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction