Multiple generic manufacturers

Phentermine (generic)

3.1

halfrx score

The cheapest weight-loss drug there is — approved for a few weeks, sold by subscription for years.

All-in, per month

Price unverified

no published priceVisit Phentermine (generic) ↗

Medication: generic
Form: pill

RxNorm 8152 for the product, 8152 for the ingredient. The codes the US National Library of Medicine assigns, so this page names one specific thing rather than a brand that could mean several.

Pharmacies acquire phentermine 37.5 mg at $0.068 a tablet — $2.05 for a 30-day supply — under the federal NADAC survey effective 17 December 2025. What a patient pays is that plus a pharmacy margin, or a telehealth membership of $30 to $99 a month layered on top of it. halfrx has not verified a retail figure it would print, so no price is shown here.

What this page used to say

2026-09-12 — Removed: "the cheapest drug in the category by two orders of magnitude". Was: The cheapest drug in the category by two orders of magnitude: pharmacies acquire it at $0.068 a tablet, about $2 for a 30-day supply, under the federal NADAC survey. Now: Pharmacies acquire it at $0.068 a tablet, about $2 for a 30-day supply, under the federal NADAC survey. That is what a pharmacy pays, not what it charges you.
2026-09-11 — A point in its favor that no longer stood. Was: The cheapest drug in the category by two orders of magnitude: $0.068 a tablet at pharmacy acquisition cost against $263 for one Zepbound pen. Now: The cheapest drug in the category by two orders of magnitude: pharmacies acquire it at $0.068 a tablet, about $2 for a 30-day supply, under the federal NADAC survey.
2026-09-11 — Reactions the phentermine label names. Was: raised heart rate, raised blood pressure, insomnia, dry mouth, constipation, restlessness. Now: raised heart rate, raised blood pressure, restlessness, dizziness, insomnia, headache, dry mouth, diarrhea, constipation.
2026-09-10 — The label quoted for phentermine was a repackager's copy. Was: FDA prescribing information for phentermine hydrochloride — Preferred Pharmaceuticals Inc., a repackager. Now: FDA prescribing information for phentermine hydrochloride tablets (Aurolife Pharma), version 8 of 15 June 2026.
2026-09-05 — Stopped claiming a 5% incidence threshold and a frequency table for a label that has neither, and added a missing contraindication on the side-effects page. Was: 'Reactions the label reports in at least 5% of patients' and 'A frequency table with exact percentages is in the label itself'. Contraindications listed seven items. Now: The page says the label names its reactions by organ system, in prose, with no incidence rates, so there is no threshold and no table. Contraindications add 'Known hypersensitivity or idiosyncrasy to the sympathomimetic amines'.

Every correction on this site, dated →

How much does Phentermine (generic) cost a month?

halfrx records no verified price for Phentermine (generic): nothing it publishes states an all-in monthly figure, so this medication carries no price here rather than a guess. What it costs once titrated is not published, which is a fact about the seller rather than a gap in the data. No FTC action, state action, BBB F grade or FDA warning letter is recorded against it. A pharmacy acquires the same drug for about $2 a month under the federal NADAC survey, which is the comparison the price above is worth reading beside. It scores 3.1 out of 10 on a published formula that is arithmetic over the facts on this page, not an editor's opinion. The medication is a generic. The page rests on 3 cited sources, at least one of them a manufacturer, regulator or journal. Nothing without a verification date shows a price on this site, because a figure nobody checked is not a price.

No clinician has reviewed this page. Label and trial statements are quoted from the FDA label or the trial cited beside them. General guidance is marked as such, and every price carries the date it was verified. That is sourcing, not medical review. What we do and do not check · Who checked the price

Controlled substanceWeaker moleculeNo published priceStrict dosing rules

What is good about Phentermine?

+Pharmacies acquire it at $0.068 a tablet, about $2 for a 30-day supply, under the federal NADAC survey. That is what a pharmacy pays, not what it charges you.[2]
+Covered by more Medicaid programs than any GLP-1 — seven states cover an older weight-loss agent while covering no GLP-1 at all.[3]
+One tablet each morning, no injection, no titration schedule beyond a possible half dose.[1]

What are the downsides of Phentermine?

−Approved for a few weeks only. Every monthly subscription selling it as ongoing therapy is using it off the label's own duration.[1]
−Schedule IV controlled substance, chemically related to the amphetamines, with the dependence warnings that follow from that.[1]
−Stopping after prolonged high dosing brings extreme fatigue and depression, per the label — which is a hard exit from a subscription that sold it as maintenance.[1]
−No cardiovascular outcome data of the kind the GLP-1s now carry, and contraindicated where blood pressure is uncontrolled.[1]

How this score is built

0.0/3.5Evidence — no weight-management trial figure recorded
3.0/3Approval — FDA approved as a short-term adjunct — the label says 'a few weeks' — for BMI 30 or more, or 27 with a risk factor such as controlled hypertension, diabetes or hyperlipidemia
0.0/2.5Cost — no verified price
0.1/1Caveats — −0.9: controlled substance −0.2, weaker molecule −0.5, strict dosing rules −0.2

The full formula →

Clinical evidence

FDA approved as a short-term adjunct — the label says 'a few weeks' — for BMI 30 or more, or 27 with a risk factor such as controlled hypertension, diabetes or hyperlipidemia

The label does not carry a modern trial figure; it states in its own words that the usefulness of this class 'should be measured against possible risk factors', and it is not recommended for long-term use.

A pharmacy acquires this for about $2 a month under the federal NADAC survey. What that says about the price you are quoted →

What you can take instead of Phentermine, with each one's verified price →

What Phentermine costs without insurance, and every route to the same drug →

What the label says goes wrong, and who cannot take it →

Maintenance dose 37.5 mg once daily, in the morning. The full schedule, and what each step costs →