Hey Product Hunt! I built Effect Curve because the numbers on a medication label never answer the question I actually have on a normal day: when will this kick in, when is it strongest, and when will it stop working - especially with a coffee on top and a second dose at lunch. How it works: - Search a substance (meds, caffeine, common supplements), enter dose and time - It draws a felt-effect curve for the day: kicks in, strongest, wears off, how long it lasts - and for stimulants, the crash - Stack multiple substances and doses on one timeline, switch routes (IR vs XR), tell it "with food" or "daily user" and the shape updates What makes it different: - The timing is fitted to published clinical figures (onset and duration of action), not vibes - It's honest about its limits. For drugs where a single dose has nothing to feel the same day (SSRIs, statins, antibiotics), it refuses to draw a curve and tells you why - Privacy by architecture: no accounts, no analytics, nothing you type ever leaves the page. The only network request is the substance search The caveat the app repeats on every curve: these are illustrative estimates from population data. People vary enormously. It is not a dosing tool and not medical advice - it's a way to see the shape of your day. It's free, open source (github.com/Open-Fitness/effect-curve), and runs in any browser with no install. I'd love to hear: which substance did you try first, and did the curve match your experience?

Effect Curve

Felt medication effect over time

Felt medication effect over time