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Methaqualone Facts

Depressant; Sedative; Hypnotic; Quinazolinone; GABA-A receptor positive allosteric modulator

Description

Methaqualone — Quaaludes, ludes, Mandrax — is a synthetic depressant of the quinazolinone class. It enhances GABA, the brain's main inhibitory signaling system, producing sedation, muscle relaxation, and a distinctive physical euphoria.[1]

Subjective effects include warm sedation, muscle relaxation, euphoria, disinhibition, and a distinctive tingling in the lips and fingertips.[2] The experience is defined by bodily heaviness and emotional openness — social barriers dissolve and the body sinks into deep relaxation.

Methaqualone produces rapid physical dependence and can kill through respiratory depression at higher doses.[3] Tolerance builds along two independent routes, driving dose escalation; combining it with alcohol dramatically amplifies the risk for at least three days after use.[4][5]

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 75 mgLight150 – 300 mgCommon300 – 500 mgStrong500 – 600 mgHeavynot recorded

Starts in 20 – 45 minLasts 5 – 8 hoursAfter-effects 6 – 8 hours

Body and dependence

Acute toxicity
High
Chronic toxicity
High
Physical dependence
High
Psychological dependence
High
Withdrawal
Severe · fatal · medical supervision
Compulsive redosing
High

Tolerance

Builds
Rapid
Fully resets after
10 days
Carries over to
benzodiazepines; barbiturates; alcohol; GHB; GABAergic depressants

Effectslikely at a common dose

Perception
none likely · 8 possible, including Vestibular distortion, Spatial disorientation, Visual acuity suppression
Body
Sedation; Muscle relaxation; +11 possible, including Dizziness, Motor control impairment, Nystagmus (eye wobbles)
Thinking
Cognitive impairment; +17 possible, including Analysis suppression, Decision impairment, Information processing suppression
Feeling
Anxiety suppression; +1 possible
Self
none likely · 3 possible, including Craving
Time
none likely · 1 possible, including Temporal disorientation

Who shouldn't take it

Absolute
Respiratory insufficiency; Seizure disorders; CNS depressant co-use; Alcohol use (within 3 days); Baclofen; Opioid co-use
Relative
History of substance use disorders; Hepatic impairment; Pregnancy; CYP3A4 inhibitors

Combinations61 recorded

Lethal (2)
Baclofen; Opioids
Dangerous (21)
Alpha-2 adrenergic receptor antagonist; Antipsychotics; Atypical antipsychotics; Benzodiazepines; Buprenorphine, Kratom; Cannabis, THC; Clonidine, Guanfacine; Gabapentin, Pregabalin; GHB, Baclofen; GHB, GBL; Local anesthetics; Naltrexone; SNRIs; Stimulants; Synthetic cannabinoids; Ibogaine; Ketamine, DXM, PCP; MAOIs; NSAIDs; Poppers (Alkyl nitrites); Poppers, Nitrates
Caution (26)
See full page: psychedex.org/substances/methaqualone
Not graded (12)
Not listed never means safe.

Seek help immediately if

  • Extreme drowsiness — can't stay awake or be roused
  • Confusion, slurred speech, severe loss of coordination
  • Slow, shallow, or irregular breathing
  • Unconsciousness / unresponsive; limp, floppy body
  • Blue lips or fingertips
  • Vomiting while sedated (choking / aspiration risk)
  • Cold, clammy skin; weak pulse

What to do

  1. Try to wake them — shout, firm sternal rub
  2. If unresponsive or breathing is impaired, call emergency services
  3. Place them in the recovery position — critical, they can choke on vomit
  4. Monitor breathing continuously; be ready to give rescue breaths / CPR
  5. Never leave them alone to "sleep it off"
  6. Do not give other drugs, stimulants, or more depressants

Most depressant overdoses resolve with airway protection, breathing support, and monitoring. The danger is respiratory depression and choking on vomit — sharply worse when combined with opioids or alcohol. GHB/GBL overdoses often involve sudden deep unconsciousness and may self-resolve, but airway protection is essential.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1 · Not medical advice

References

  1. [1]
    ^Hammer H, Bader BM, Ehnert C, Bundgaard C, Bunch L, Hoestgaard-Jensen K, Schroeder OH, Bastlund JF, Gramowski-Voss A, Jensen AA (2015) A Multifaceted GABAA Receptor Modulator: Functional Properties and Mechanism of Action of the Sedative-Hypnotic and Recreational Drug Methaqualone (Quaalude) — Molecular Pharmacology doi:10.1124/mol.115.099291
  2. [2]
    ^Hicks TP, Kaneko T, Oka JI (1990) Receptive-field size of S1 cortical neurones is altered by methaqualone via a GABA mechanism — Canadian Journal of Neurological Sciences PMID:2311013
  3. [3]
    ^Doyno CR, White CM (2021) Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank — Journal of Clinical Pharmacology doi:10.1002/jcph.1922
  4. [4]
    ^Tilstone WJ, Reavey PC (1978) Interaction of ethanol with amylobarbitone, phenobarbitone and methaqualone — Research Communications in Chemical Pathology and Pharmacology PMID:644120
  5. [5]
    ^Ballinger B, Browning M, O'Malley K, Stevenson IH (1972) Drug-metabolizing capacity in states of drug dependence and withdrawal — British Journal of Pharmacology PMID:5085238
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