Plan a day of supplements on one chart
Put what you take on a 24-hour line. Each supplement rises and falls from its published half-life, and the spacing check shows which timing rules from drug labels and studies your schedule crosses. Every number links to its source.
Day Simulator · Kymata Health 13 supplements sourced Checked Oct 21, 2026 Saved in this browser only How it works
Day simulator · one-compartment model · relative level, each curve scaled to its own peak
27 source quotes checked Oct 21What you take 5 on the chart · add or remove
- spaceIron 2.5 hours after levothyroxine; the source gives at least 4 hours. The levothyroxine label says not to take it within 4 hours of iron or calcium supplements. FDA label
- Caffeine at melatonin time (22:00): 16% of its peak, from the average half-life. Smokers clear it faster.
- Caffeine taken 07:30 peaks around 08:18
- Melatonin taken 22:00 peaks around 22:48
- Ashwagandha taken 20:00 peaks around 21:12
What each line is drawn from
3 on the chart · every number quoted from its source| Supplement | Taken | Half-life | Time to peak | Studied in |
|---|---|---|---|---|
| Caffeinecaffeine in plasma, immediate-release | 07:30peak about 08:18 | 4.3 h to 5.8 h PMID 19125908PMID 36602880 | 50 min PMID 36602880 | Healthy adult non-smokers, single caffeine capsule (3 to 5 mg/kg, or 200 mg).Shorter in smokers (3.0 h in the same study); longer in pregnancy, with oral contraceptives and in liver disease. A sustained-release capsule peaks later. Time to peak and the higher half-life come from one 15-person study with an author from Nutriventia Limited. |
| Melatoninmelatonin in plasma, immediate-release | 22:00peak about 22:48 | 45 min PMID 26008214 | 50 min PMID 26008214 | Systematic review of human studies, oral immediate-release.Sustained-release products stay up longer (about 1.8 to 2.1 h in the same review). |
| Ashwagandhafour withanolides from a root extract, in plasma | 20:00peak about 21:12 | 1.7 h to 4.4 h PMID 39963957 | 1 h to 1.4 h PMID 39963957 | Healthy adults, one 400 mg dose of one root extract.One small study of one extract; other extracts may differ. |
How does the Day Simulator draw each curve?
The curves. Each supplement uses a one-compartment model: it is absorbed, reaches a peak at the time to peak the source reports, and falls by half every half-life. Taken at the same time each day, yesterday’s doses add up, so something with a half-life of days draws as a nearly flat line. Each curve is scaled to its own peak: the chart compares timing, not amounts, and says nothing about what is in anyone’s blood.
The band. Where studies report a range, the shaded band spans its low and high ends. Real people vary more than the band shows: age, other medicines, food, smoking, pregnancy and the product itself all move these numbers.
What is left out. A supplement appears only if a source we read prints a half-life for it in people. One with a half-life but no reported time to peak shows its dose time without a curve, because drawing one would mean guessing. Creatine, magnesium, iron, zinc, vitamin B12, vitamin C and vitamin D are left out for that reason, or because their levels are not a simple rise and fall.
The spacing check. Rules come from the prescribing information for levothyroxine and oral semaglutide, and from a study of coffee with levothyroxine. They are the label’s words, not advice for you; a pharmacist can tell you how they apply.
Where does each half-life come from?
- Caffeine (caffeine in plasma, immediate-release): “The extrapolated elimination half-lives of caffeine in the non-smokers and the smokers were 4.3 +/- 1.5 and 3.0 +/- 0.7 h respectively.” (Seng KY, J Clin Pharm Ther, 2009, PMID 19125908) “Similarly, mean t½ was 7.07 ± 3.48h for SR-Caffeine compared to 5.78 ± 2.11h for IR-Caffeine (p = 0.04189).” (Thanawala S, J Diet Suppl, 2024, PMID 36602880)
- Melatonin (melatonin in plasma, immediate-release): “T1/2 was 45 min in both administration routes.” (Harpsøe NG, Eur J Clin Pharmacol, 2015, PMID 26008214)
- L-theanine (L-theanine in plasma): “Since the half-life of theanine is about 1 hour, it should be mostly eliminated from the milk in 3 to 5 hours.” (NICHD, Drugs and Lactation Database (LactMed), NCBI Bookshelf, 2025, PMID 40460226)
- Ashwagandha (four withanolides from a root extract, in plasma): “Further, t1/2 (1.696-4.377 h), lambda_z (0.141-0.282 L/h), Cl/F (0.065-0.954 mg/(ng/ml)/h), AUMC 0-inf_obs (21.720-80.485 ng/mL*hˆ2) and MRT 0-inf_obs (3.680-7.516 h) also differed for each bioactive.” (Sharma E, Drug Metab Pers Ther, 2025, PMID 39963957)
- Alpha-lipoic acid (alpha-lipoic acid in plasma): “The difference in mean t(1/2) for the two oral doses and the i.v. dose (in the range of 25.3-32.7 min) was not statistically significant.” (Teichert J, Int J Clin Pharmacol Ther, 1998, PMID 9876998)
- Taurine (taurine in plasma above the body’s own level): “Plasma elimination half-life (T(1/2)) and the ratio of clearance/bioavailability (Cl/F) were 1.0 ± 0.3 hr and 21.1 ± 7.8 L/hr, respectively.” (Ghandforoush-Sattari M, J Amino Acids, 2010, PMID 22331997)
- Curcumin (curcumin conjugates (breakdown products) in plasma): “The T(max) and t(1/2) were estimated to be 3.29 +/- 0.43 and 6.77 +/- 0.83 h.” (Vareed SK, Cancer Epidemiol Biomarkers Prev, 2008, PMID 18559556)
- CoQ10 (CoQ10 (ubiquinone) in plasma): “After oral administration of 100 mg of d5-CoQ10 to 16 healthy male subjects, the mean plasma CoQ10 level attained a peak of 1.004 +/- 0.370 micrograms/ml at 6.5 +/- 1.5 h after administration, and the terminal elimination half-life was 33.19 +/- 5.32 h.” (Tomono Y, Int J Clin Pharmacol Ther Toxicol, 1986, PMID 3781673) “The estimated elimination half-life (t(1/2)) was 92.3 hr after a single oral dose of CoQ(10)-P5P-PC, 38.2 hr with CoQ(10) (NPN 02176955), and 80.7 hr with CoQ(10) (DIN 02231736).” (Evans M, J Diet Suppl, 2010, PMID 22432561)
- Fish oil (EPA) (EPA in plasma, from prescription EPA ethyl ester): “The plasma elimination half-life (t 1/2 ) of EPA is approximately 89 hours.” (Amarin Pharma Inc., FDA prescribing information, DailyMed (version of Mar 30, 2026), 2026, label)
- 5-HTP (5-HTP in plasma): “Half-lives of 2.2--3.0 hrs. were obtained following oral administration of a single dose of 5-hydroxytryptophan with or without pretreatment.” (Magnussen I, Acta Pharmacol Toxicol (Copenh), 1978, PMID 309271)
- Biotin (biotin in plasma): “The elimination half life time of the administered biotin dose from plasma amounted to 1 hour, 50 minutes.” (Bitsch R, Int J Vitam Nutr Res, 1989, PMID 2722429)
- Fish oil (DHA) (a labelled DHA tracer in plasma): “The mean (±SEM) plasma (13)C-DHA half-life was 4.5 ± 0.4 d at baseline compared with 3.0 ± 0.2 d while taking the supplement (P < 0.0001).” (Plourde M, Am J Clin Nutr, 2014, PMID 24829492)
- Quercetin (quercetin in plasma): “The oral clearance (CL/F) was high (3.5 x 10(4)l/h) with an average terminal half-life of 3.5 h for quercetin.” (Moon YJ, Biopharm Drug Dispos, 2008, PMID 18241083)
Questions about the Day Simulator
What does the Day Simulator show?
A 24-hour chart of what you take: each supplement rises and falls from its published half-life and time to peak, and a spacing check shows which timing rules from drug labels and studies your schedule crosses, with the source for each.
How long apart should levothyroxine and iron or calcium be?
The levothyroxine (Synthroid) label says not to take it within 4 hours of iron or calcium supplements. The chart shades that window and flags anything placed inside it; a pharmacist can tell you how it applies to you.
Are the curves my blood levels?
No. Each curve is a population-average shape scaled to its own peak, from small studies. It compares timing, not amounts, and says nothing about what is in anyone’s blood.