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MDMA Pharmacokinetics

Plasma concentration model based on published population PK parameters. Shows how dose, body weight, and redosing affect concentration over time.

⚠ Always test your substance before use. Street MDMA is frequently adulterated with dangerous compounds including methamphetamine, synthetic cathinones, and PMA/PMMA — which have caused deaths at doses people considered safe. PMA has a much lower lethal dose and slower onset than MDMA, causing people to redose thinking it is not working. A reagent test kit (Marquis, Mecke, Simon's) takes 30 seconds and can save your life. Available for example from DanceSafe.
Population-average PK model. ~7% of Europeans are CYP2D6 poor metabolisers and reach 2–3× higher concentrations at the same dose. This is not a safety guarantee.

Personal details

kg

Vd scales with body weight (~7 L/kg). Lighter individuals reach higher concentrations at the same dose.

Pill details

mg

Dutch pills commonly range 100–250mg. High-dose pills (>200mg) carry significantly higher risk.

⚠ Assuming 100% purity. Actual content may differ significantly. Test your substance.

Effective MDMA per pill: 150.0 mg

Dose schedule

First dose
150.0mg
Total: 150.0 mg MDMA(2.14 mg/kg)
SHOW24h
0–50 ng/mL Sub-threshold50–100 ng/mL Threshold / mild100–200 ng/mL Active effects200–350 ng/mL Strong effects350–500 ng/mL Very strong — caution500–800 ng/mL Dangerous territory

Why higher doses are disproportionately dangerous: MDMA inhibits CYP2D6 — the enzyme that metabolises it — at higher concentrations (autoinhibition). Clearance slows as concentration rises, so doubling the dose more than doubles peak concentration.

t½ ≈ 8.5h means: significant MDMA remains present the next morning. Sleep deprivation combined with elevated concentrations substantially increases serotonergic neurotoxicity risk.

CYP2D6 variation: ~7% of Europeans are poor metabolisers and reach 2–3× higher concentrations at identical doses. There is no way to know your metaboliser status without genetic testing.

Dangerous combinations

MAOIs (moclobemide, phenelzine, etc.)LETHAL

Prevents serotonin breakdown — can cause fatal serotonin syndrome within minutes. Never combine under any circumstances.

SSRIs / SNRIs (fluoxetine, venlafaxine, etc.)SEVERE

Serotonin syndrome risk. SSRIs also reduce MDMA effects by competing at the serotonin transporter — leading people to dangerously redose.

LithiumSEVERE

High risk of seizures. Absolutely avoid.

TramadolSEVERE

Tramadol inhibits serotonin and norepinephrine reuptake and significantly lowers seizure threshold. Combined with MDMA this creates serotonin syndrome risk and seizure risk. Sometimes prescribed for pain — if you or someone around you takes tramadol, do not combine with MDMA.

Cocaine / AmphetaminesHIGH

Combined cardiovascular strain. Dangerous hyperthermia and heart rate elevation. Risk of cardiac events.

KetamineMODERATE–HIGH

Both have dissociative and serotonergic elements. Combined CNS depression with MDMA cardiovascular stimulation creates unpredictable physiological stress. Strong disorientation and loss of situational awareness. Difficult to assess own condition or seek help if needed.

AlcoholMODERATE

Both cause dehydration. Alcohol masks MDMA effects and vice versa, leading to overconsumption of both. Increased neurotoxicity risk.

CannabisLOW–MODERATE

Can intensify anxiety and paranoia significantly. May worsen comedown. Individual variation is large.

Struggling with MDMA use? Jellinek.nl and Trimbos.nl offer free, confidential support.