Educational framing only — not medical advice, not a treatment recommendation, and not a substitute for reading the underlying trial.
Back to L-citrulline vs L-arginine guide
NNT
—
ARD —
Waiting for inputs
Formula
ARD = EER − CER · NNT = ⌈100 ÷ ARD⌉
Trial reference
Event rates
Result wording
Enter control and experimental event rates — or pick a trial preset.
Worked example — CER 8.3% · EER 50% → ARD 41.7 pp · NNT 3 (Cormio 2011, 1 month)
Educational only — not medical advice. Disclaimer.
How to use this
- CER — % of people with the event in the control / placebo arm.
- EER — % with the event in the experimental arm.
- ARD — EER minus CER, in percentage points.
- NNT — ceiling of 1 ÷ ARD (as a proportion). Always pair with a time horizon.
- Presets — published dichotomous figures from our guides. Small-n caveats stay attached.
Preset sources
- Cormio 2011 · citrulline (single-blind pilot, n=24, 1 month, EHS 4 endpoint; 95% CI not reported). PMID 21195829. Trial floor: citrulline dose entry; context: citrulline vs arginine for ED.
- Menafra 2022 · arginine (multicentre RCT, n=98, 3 months, IIEF-6 normalization endpoint). PMID 34973154. Trial floor: arginine dose entry; same guide for context.
What this does not do
Continuous outcomes (mean IIEF change, hair count per cm², kg lost) do not get an NNT. Relative risk or odds ratio without baseline rates are not enough. Observational studies are out of scope. If the experimental arm does worse, use NNH framing — this tool flags that case instead of inventing a benefit NNT.