Is phentermine a controlled substance?

Yes. Phentermine is a controlled substance in both countries. In the United States it is in Schedule IV of the Controlled Substances Act, with DEA code 1640 and an N in the narcotic column. In the United Kingdom it is a Class C drug under the Misuse of Drugs Act 1971 and sits in Schedule 3 of the Misuse of Drugs Regulations 2001.

What is phentermine?

Phentermine hydrochloride is a sympathomimetic amine anorectic. The DEA list gives these other names: Ionamin, Fastin, Adipex-P, Obe-Nix and Zantryl.

The label cited here is for Phentermine Hydrochloride Tablets from Aurolife Pharma, published on DailyMed on June 15, 2026. Its Indications section reads:

Phentermine hydrochloride tablets are indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity

The label goes on to describe the body mass index thresholds for patients. Section 12.1 says the drug has pharmacologic activity similar to amphetamine, and that it belongs to a group commonly known as anorectics.

The label is plain about the limits of this class of drug. It says the limited usefulness of agents of this class, including phentermine, should be measured against the possible risk factors inherent in their use. Section 12.2 adds that typical actions of amphetamines include central nervous system stimulation and elevation of blood pressure, and that tachyphylaxis and tolerance have been demonstrated with all drugs of this class in which these phenomena have been looked for. Section 12.1 notes that it has not been established that the primary action of such drugs in treating obesity is appetite suppression, since other central nervous system actions or metabolic effects may also be involved. Whether the drug suits a given person is a decision for them and their prescriber.

What does Schedule IV mean for phentermine?

Phentermine is listed at 21 CFR 1308.14(f)(9), under the Schedule IV stimulants. The label agrees: section 9.1 states that phentermine is a Schedule IV controlled substance.

Under 21 U.S.C. 812(b), a Schedule IV placement requires findings of a low potential for abuse relative to Schedule III, a currently accepted medical use in the United States, and that abuse may lead to limited physical or psychological dependence relative to Schedule III. The wider system is explained on the drug schedules page.

The practical side is in 21 CFR 1306.22. A prescription for a Schedule III or IV drug cannot be filled or refilled more than six months after the date it was issued, and it cannot be refilled more than five times. Unlike Schedule II drugs, refills are allowed within those limits. Schedule II drugs such as Adderall or fentanyl cannot be refilled at all. States and prescribers may add their own limits, and the state board of pharmacy is the authority on that.

Is phentermine a narcotic or an amphetamine?

It is not a narcotic. The DEA list marks phentermine N. In US drug law the word narcotic has a specific meaning tied to opium and opiates, which is explained in what is a narcotic. Phentermine is a stimulant-type drug, and the DEA schedule groups it with other stimulants.

It is a separate drug from amphetamine, though the label draws the link itself. Section 9.2 says phentermine is related chemically and pharmacologically to the amphetamines. The two are separate entries on the DEA list: amphetamine is Schedule II (code 1100), phentermine is Schedule IV (code 1640).

What does the phentermine label say about abuse and dependence?

Section 9.2, Abuse, says that amphetamines and other stimulant drugs have been extensively abused and that the possibility of abuse of phentermine should be kept in mind when evaluating the desirability of including a drug as part of a weight reduction program.

Section 9.3, Dependence, says abuse of amphetamines and related drugs may be associated with intense psychological dependence and severe social dysfunction. It reports that abrupt cessation after prolonged high-dose administration results in extreme fatigue and mental depression, and that chronic intoxication with anorectic drugs can include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The label ties these effects to high-dose, prolonged use. A patient with questions about their own prescription should speak to the prescriber or pharmacist.

What is phentermine's status in the UK?

The Home Office list of the most commonly encountered controlled drugs (updated April 1, 2025) shows phentermine as Class C under the Misuse of Drugs Act 1971 and Schedule 3 under the Misuse of Drugs Regulations 2001. The three classes are described on UK drug classes. Schedule 3 is one of five schedules in the 2001 Regulations, which set the rules on prescribing, supply and records for each group of drugs. The Home Office list is not exhaustive, so the Act and Regulations on legislation.gov.uk are the final reference.

Other UK Class C, Schedule 3 drugs on the same list include tramadol, gabapentin and pregabalin.

Related pages

• Is Adderall a controlled substance?
• Is Vyvanse a controlled substance?
• What is a controlled substance?
• DEA drug schedules I to V

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