Is phentermine a controlled substance? Yes: Schedule IV.

The short answer

Yes. Phentermine is a Schedule IV controlled substance under federal law. It is listed at 21 CFR 1308.14(f)(9) with DEA Controlled Substances Code Number 1640. "Adipex" is a brand name and does not appear in the schedule text; the listing is for the substance itself.

Two sources sit behind that answer. Title 21 U.S.C. 812 is the statute that sets out what each schedule means. 21 CFR 1308.11 to 1308.15 is the regulation that lists the substances in each schedule. The CFR text here was read from the eCFR for the issue current through November 10, 2026, and the statute from the 2024 U.S. Code edition on govinfo.

This is a classification page. It has no dosing, use, acquisition or synthesis information.

The phentermine entry, quoted

Paragraph (f) of 1308.14 is headed "Stimulants". It covers any material, compound, mixture or preparation that contains any quantity of the listed substances "having a stimulant effect on the central nervous system, including its salts, isomers and salts of isomers". Item (9) is "Phentermine 1640". The full paragraph has 14 items, listed below.

Look-alike names sit in different places. Schedule III, at 1308.13(b), lists "Chlorphentermine 1645" and "Clortermine 1647". Plain phentermine is in Schedule IV. When you check a drug, match the exact name on the line, not a similar one.

Brand names versus substances

Section 1308.14(a) says each schedule covers substances "by whatever official name, common or usual name, chemical name, or brand name designated, listed in this section". In practice the entries use official or chemical names. A text search of 1308.11 to 1308.15 for "Adipex" finds nothing.

To find what a product contains, read the ingredients on its FDA-approved label. FDA's DailyMed database publishes them.

Statute and findings

Under 21 U.S.C. 812(b)(4), a Schedule IV substance has "a low potential for abuse relative to the drugs or other substances in schedule III". It also has "a currently accepted medical use in treatment in the United States". Abuse "may lead to limited physical dependence or psychological dependence relative to the drugs or other substances in schedule III".

The initial schedules in 812(c) do not name phentermine. It was added later by rulemaking. The statute gives the test and the CFR gives the list.

The Schedule IV listing, in the CFR's own words

The lead-in of 21 CFR 1308.14(f) reads:

(f) Stimulants. Unless specifically excepted or unless listed in another schedule, any material, compound, mixture, or preparation which contains any quantity of the following substances having a stimulant effect on the central nervous system, including its salts, isomers and salts of isomers:

Entries from the Schedule IV stimulants at 1308.14(f):

• (1) Cathine 1230
• (2) Diethylpropion 1610
• (3) Fencamfamin 1760
• (4) Fenproporex 1575
• (5) Mazindol 1605
• (6) Mefenorex 1580
• (7) Modafinil 1680
• (8) Pemoline 1530
• (9) Phentermine 1640
• (10) Pipradrol 1750
• (11) Serdexmethylphenidate 1729
• (12) Sibutramine 1675
• (13) Solriamfetol 1650
• (14) SPA 1635

What the statute requires for Schedule IV

Title 21 U.S.C. 812(b) says a substance "may not be placed in any schedule unless the findings required for such schedule are made". The three Schedule IV findings are quoted under "Statute and findings" above.

Those findings are the legal test for scheduling. They are not a medical statement and do not describe any person's use of a drug. The CFR then records which substances were placed in each of the five schedules.

How to read and re-check a schedule listing

Each schedule entry follows the same pattern. A lead-in sentence says what class of substance follows, and often that salts, isomers and salts of isomers are included. Each line then gives a substance name and, in most sections, a four-digit DEA Controlled Substances Code Number. The code identifies the line. It is not a rating of risk.

1. Open the section for the schedule you want: 21 CFR 1308.11 (Schedule I), 1308.12 (II), 1308.13 (III), 1308.14 (IV) or 1308.15 (V) in the eCFR.
2. Find the paragraph for the class of substance: opiates, opium derivatives, hallucinogenic substances, depressants, stimulants, narcotic drugs, anabolic steroids and so on, each introduced by a lead-in sentence.
3. Read the entry by its official or chemical name, not by brand name, and note the four-digit DEA Controlled Substances Code Number printed beside it.
4. Check for words such as "unless specifically excepted" or "except" in the lead-in or the line itself, which limit what the entry covers.
5. Confirm the date. The eCFR shows an "as of" date, and schedules change by rulemaking.

Limits of this page

This page quotes 21 CFR 1308.11 to 1308.15 as published in the eCFR, current through November 10, 2026, and part of 21 U.S.C. 812. The eCFR shows these last-amended dates: 1308.11 November 6, 2026; 1308.12 December 21, 2022; 1308.13 October 30, 2026; 1308.14 August 31, 2026; 1308.15 June 1, 2022.

It reports the federal classification only. It does not cover state law, registration, record-keeping or prescription rules, penalties, or any use of a drug. It cannot tell you whether a particular product, person or activity is lawful.

The eCFR is an editorial compilation, not the official legal edition of the Federal Register, and schedules change by rulemaking. Check the current text and DEA before relying on it. Take legal questions to a qualified attorney and medicine questions to a pharmacist or physician.

Sources

Sources opened and read November 12, 2026.

• eCFR: 21 CFR 1308.14, Schedule IV (current through November 10, 2026) (read November 12, 2026)
• eCFR: 21 CFR part 1308, Schedules of controlled substances (current through November 10, 2026) (read November 12, 2026)
• GovInfo: 21 U.S.C. 812, Schedules of controlled substances, United States Code, 2024 Edition (read November 12, 2026)
• eCFR: 21 CFR 1308.13, Schedule III (current through November 10, 2026) (read November 12, 2026)