What drugs are classified as Schedule 1 under the Controlled Substance Act (CSA)?

Schedule I Controlled Substances

Schedule I drugs under the Controlled Substances Act include marijuana, heroin, LSD, psilocybin, MDMA, and numerous synthetic cannabinoids and cathinones—substances defined as having high abuse potential, no currently accepted medical use in the United States, and lack of accepted safety for use under medical supervision. 1, 2

Defining Characteristics of Schedule I

Schedule I classification requires three criteria under the Controlled Substances Act of 1970:

• High potential for abuse and dependency 1
• No currently accepted medical use in treatment in the United States 1, 2
• Lack of accepted safety for use even under medical supervision 1

Specific Schedule I Substances

Classic Psychedelics and Entactogens

• LSD (lysergic acid diethylamide) remains Schedule I despite emerging research showing potential therapeutic benefit in treatment-resistant depression and end-of-life anxiety 2
• Psilocybin (the active compound in "magic mushrooms") is Schedule I, though contemporary human studies demonstrate promise for psychiatric conditions refractory to conventional treatments 2
• MDMA (3,4-methylenedioxymethamphetamine) is Schedule I, despite ongoing research for post-traumatic stress disorder treatment 2
• Ayahuasca and its constituent DMT remain Schedule I substances 2

Cannabis and Cannabinoids

• Marijuana has been classified as Schedule I since 1970, though multiple states have legalized medical and recreational use 1
• Synthetic cannabinoids including PB-22, 5F-PB-22, AB-FUBINACA, and ADB-PINACA were placed in Schedule I due to imminent public safety hazards 3, 4
• The 2018 Farm Bill removed hemp (cannabis with <0.3% THC) from the CSA definition of marijuana, but marijuana itself remains Schedule I 1

Synthetic Cathinones

• Ten synthetic cathinones were permanently placed into Schedule I in 2017: butylone, naphyrone, pentylone, pentedrone, 3-fluoro-N-methylcathinone, 4-FMC, 4-methyl-N-ethylcathinone, 4-methyl-pyrrolidinopropiophenone, alpha-pyrrolidinobutiophenone, and α-pyrrolidinopentiophenone 5
• These amphetamine analogues produce stimulant effects with rewarding properties and high abuse potential 5

Opioids

• Heroin (diacetylmorphine) is Schedule I, distinguishing it from other opioids like morphine, oxycodone, and methadone which are Schedule II due to accepted medical uses 6

Critical Distinction from Other Schedules

Schedule I differs fundamentally from Schedule II substances (morphine, oxycodone, hydromorphone, fentanyl, methadone) and Schedule III substances (hydrocodone combinations) because those schedules recognize accepted medical use despite abuse potential. 6, 7

The scheduling process involves both the Department of Health and Human Services (through FDA and NIDA) and the Drug Enforcement Administration, utilizing an Eight-Factor Analysis to evaluate abuse potential, pharmacology, scientific evidence, and public health risk 5

Important Caveats

• FDA approval can create exceptions: Epidiolex® (pharmaceutical-grade cannabidiol) became the first cannabis-derived drug approved by FDA in June 2018 for severe epilepsy, effectively removing it from practical Schedule I restrictions despite cannabis remaining Schedule I 1
• Temporary scheduling authority allows DEA to place substances in Schedule I for up to two years while permanent scheduling is completed, as occurred with synthetic cannabinoids 3, 4
• The passage of the Controlled Substances Act in 1970 significantly limited psychedelic research for decades, though recent renewal of interest has led to breakthrough therapy designations for some Schedule I substances in clinical trials 2