Source-backed half-life profile
MDMA half-life calculator
MDMA is where the calculator needs humility. A curve can show parent-compound persistence, but dose, temperature, co-exposures, and nonlinear features make the source context matter.
Every curve begins at 100%. No dose or measured body concentration is assumed.
X-axis: elapsed time. Y-axis: modeled percentage of the relative starting point remaining. The shaded band shows the reported half-life range. This is a mathematical visualization, not a personal concentration estimate.
What a careful reader should notice first
This page is most useful for showing why a same-day tail can remain meaningful without pretending to estimate mood, cardiovascular strain, toxicity, or redosing risk.
Source angle
The better reading question is whether a source is discussing controlled pharmacokinetics, physiological measures, or broader toxicology context.
Do not use it for
Do not use the chart as a redosing, recovery, hydration, temperature, or impairment guide.
Best next step
Use the nonlinear kinetics and half-life-versus-duration guides before comparing MDMA with MDA.
MDMA: evidence and interpretation notes
Eight hours comes from extended human sampling
Kolbrich and colleagues followed MDMA and several metabolites in 17 young adults, with plasma sampling extending far beyond the initial observation period. Mean parent-MDMA half-lives were approximately 7 to 8 hours, while MDA and HMMA persisted longer. HalfLifeDB rounds that parent estimate to eight hours and displays an 8-to-9-hour literature range.
The distinction between parent and metabolites is important. The line follows MDMA itself; it does not combine HMMA, MDA, HMA, or downstream physiological measurements into one quantity.
| Evidence source | What it contributes | Important limit |
|---|---|---|
| Kolbrich controlled study | Seventeen-participant parent and metabolite profiles with extended sampling | A controlled cohort cannot represent unknown real-world composition or co-exposures |
| de la Torre nonlinear study | Direct evidence that concentration increases were not proportional across study conditions | A simple first-order curve cannot reproduce saturating or self-inhibiting metabolism |
| Irvine plasma study | Places concentrations beside physiological measures | Association does not make a remaining percentage a safety measure |
| StatPearls toxicology chapter | Clinical risk context | It is not used to choose the eight-hour value |
Nonlinearity is the central model warning
The de la Torre study found that increases in measured MDMA concentrations were disproportionate across the investigated conditions, with findings consistent with saturation or inhibition of a metabolic pathway. The Kolbrich study likewise reported nonlinear patterns in exposure measures and substantial variation between participants.
This is exactly where HalfLifeDB’s equation becomes intentionally incomplete. First-order elimination assumes a constant fractional decline. If clearance changes with exposure, one fixed half-life cannot reproduce the observed concentration-time profile. The chart remains useful as a reference line, but not as a mechanistic simulation.
Why the line cannot answer a safety question
An eight-hour curve shows a meaningful same-day and overnight mathematical tail. It does not calculate temperature-related risk, cardiovascular strain, hydration needs, serotonin effects, impairment, recovery, or the consequences of repeated exposure. It also cannot verify substance identity or composition.
The page’s useful conclusion is narrower: controlled human studies place parent-MDMA elimination around the eight-hour scale, metabolites last longer, and nonlinear behavior makes exact extrapolation less reliable than the smooth line suggests.
Reading this curve
HalfLifeDB uses 8 h as a representative input for MDMA. In the simplified model, about 12.5% remains after 24 hours and about 3% remains after five half-lives, or roughly 40 h.
This sits in the same-day range. The chart is useful for seeing the bend of the curve across a day or two, but it should not be treated as a personal clock. The curve is relative: it does not estimate a person's measured concentration, effects, impairment, or time to clearance.
entactogen context
Entactogen pharmacokinetics can vary with dose, metabolism, temperature, co-exposures, and nonlinear features reported in some studies.
- The curve is not a safety or redosing guide.
- Physiologic effects can outlast or diverge from the parent-compound curve.
- Study context matters when comparing estimates.
MDMA timeline checkpoints
| Elapsed time | Modeled remaining | Reading note |
|---|---|---|
| 12 h | 35.4% | Meaningful modeled decline, not near-zero |
| 24 h | 12.5% | Long-tail portion of the model |
| 2.0 days | 1.56% | Low modeled remainder, not a clearance guarantee |
| 3.0 days | 0.20% | Low modeled remainder, not a clearance guarantee |
| 5.0 days | 0.00% | Low modeled remainder, not a clearance guarantee |
Nearby profiles by half-life
These entries sit near MDMA within the entactogen group when sorted by representative half-life. That makes them curve comparisons, not statements about equal potency, effects, or risk.
No nearby published profiles are available in this category.
Pharmacokinetics at a glance
| Representative half-life | 8 h |
|---|---|
| Reported range | 8 h to 9 h |
| Curve type | Normalized, first-order decline |
Selection note: Human pharmacology literature reports an MDMA elimination half-life of about 8 to 9 hours; the curve uses the lower end of that rounded range.
Sources and evidence context
A linked record is not automatically proof of the displayed value. Study, labeling, review, and compound identity sources serve different purposes; notes below identify limitations when they are known.
- Research abstract Kolbrich EA et al. Pharmacokinetics of MDMA in humans (2008).Controlled study in 17 young adults with extended plasma sampling; direct support for the approximately 7-to-8-hour parent-MDMA half-life.
- Full-text research de la Torre R et al. Non-linear pharmacokinetics of MDMA in humans (2000).Controlled human study showing disproportionate concentration increases and evidence of metabolism saturation across study conditions.
- Peer-reviewed source Irvine RJ et al. Plasma drug concentrations and physiological measures in MDMA users (2006).Human plasma-concentration and physiological-measure study included to keep pharmacokinetics and physiological outcomes distinct.
- Identity record PubChem Compound Summary: MDMA.Compound identity record; background only.
- Clinical reference MDMA Toxicity. StatPearls.Clinical toxicology overview; safety context only, not the numerical basis for the chart.
What this page does not answer
- It does not estimate impairment, intoxication, or fitness to drive.
- It does not predict urine, blood, saliva, or hair test results.
- It does not model repeated exposure, tolerance, withdrawal, or interactions.
- It does not replace clinician, pharmacist, toxicologist, or emergency guidance.
Continue with context
- All substance profiles
- Browse the entactogen group
- Compare this curve
- Clearance and volume of distribution
- Bioavailability, route, and formulation
- Active metabolites and parent compounds
- First-order vs nonlinear kinetics
- Detection windows vs half-life
- Reading labels and source quality
Read the medical disclaimer, methodology, and profile review log before using the model for comparison.