This study investigates whether MDMA may have a pain-reducing effect. The effect of MDMA is compared with a placebo (a substance with no active effect).

In the study, moderate pain will be artificially created in healthy participants using repeated small electrical pulses applied under the skin. At the same time, participants will take MDMA or a placebo by mouth. This allows researchers to compare how MDMA affects the artificially created pain. A total of 20 healthy volunteers will take part in this study.

Preliminary evidence from case series and small clinical trials suggests that 3,4-methylenedioxymethamphetamine (MDMA) may be promising candidates for the treatment of chronic or neuropathic pain. Moreover, MDMA potently releases serotonin, noradrenalin and oxytocin, which are implicated in the modulation of pain. However, data from rigorously conducted and randomized clinical trials are lacking. Additionally, the potential acute analgesic properties of MDMA remain poorly characterized. For instance, it is unclear whether MDMA possesses acute antinociceptive effects or if it rather modulate secondary pain phenomena such as hyperalgesia, allodynia, and/or functional pain. Here, the investigators will employ a validated electrical stimulation model in healthy volunteers that produces acute nociceptive pain but also features of chronic pain such as hyperalgesia and allodynia. The model is established for the detailed assessment of the analgesic effect of known analgesics or new compounds. Thus, the investigators will evaluate the efficacy of MDMA on different pain qualities within this model. The analgesic efficacy of MDMA 125 mg will be compared to MDMA 75 mg, MDMA 25 mg and placebo.

Inclusion Criteria:

1. Age between 18 and 75 years old
2. Sufficient understanding of the German language
3. Understanding of procedures and risks associated with the study
4. Willing to adhere to the protocol and signing of the consent form
5. Willing to refrain from the consumption of illicit psychoactive substances during the study
6. Willing not to operate heavy machinery for 48 hours after the study session.
7. Willing to use effective birth control throughout study participation
8. Body mass index between 18-34.9 kg/m2

Exclusion Criteria:

1. Relevant chronic or acute medical condition
2. Any implanted medical devices (e.g., pacemakers, neurostimulators, or metal prostheses)
3. Current or previous major psychiatric disorder (e.g. bipolar disorder, schizophrenia), current depression or anxiety disorder.
4. Psychotic disorder or bipolar disorder in first-degree relatives
5. Hypertension (SBP>140/90 mmHg) or hypotension (SBP<85 mmHg)
6. Lifetime use of MDMA on more than 20 occasions or any use within the previous two months
7. Pregnancy or current breastfeeding
8. Participation in another clinical trial (currently or within the last 30 days)
9. Use of medication that may interfere with the effects of the study medication
10. Tobacco smoking (>10 cigarettes/day)
11. Consumption of alcoholic beverages (>15 drinks/week)