L-Citrulline and medications.
L-Citrulline is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
L-citrulline is an amino acid that the body converts into L-arginine, and it does this more efficiently than taking arginine directly because it has better oral bioavailability. That conversion raises nitric oxide, which widens blood vessels. The evidence is Grade B for erectile function and cardiovascular effects, and Grade B for athletic performance. Trials by Cormio, Figueroa, Bailey and Pérez-Guisado suggest it may help mild-to-moderate erectile dysfunction at around 1.5g a day, modestly lower blood pressure, and improve exercise performance and muscle soreness at 3 to 6g. The effects are modest rather than dramatic. Two interactions follow directly from the vasodilation mechanism: it adds to the effect of PDE5 inhibitors like sildenafil and tadalafil, and it stacks with blood-pressure-lowering medication, so both are worth flagging to a GP and monitoring. It is otherwise very well tolerated, with only mild stomach effects at higher doses. A practical point: match the dose to the goal, since ED and performance protocols differ.
Below are the 2 documented pairs we have explicitly assessed for L-Citrulline: 2 amber. The pairs cluster around 1 mechanism: Additive vasodilation. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Additive vasodilation
L-citrulline raises nitric oxide, which widens blood vessels, and sildenafil works on the same nitric oxide pathway. Combining them could add up to a larger drop in blood pressure, so watch for dizziness, flushing, or faintness, particularly in the few hours after a sildenafil dose. Tell your GP if you take both.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-citrulline raises nitric oxide, which widens blood vessels, and tadalafil works on the same nitric oxide pathway. Combining them could add up to a larger drop in blood pressure, so watch for dizziness, flushing, or faintness. Tadalafil lasts much longer than sildenafil, so the window where this matters is wider. Tell your GP if you take both.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
For adults over 18.
This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, pharmacist, or specialist before making them, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologySomething missing?
If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.