Phendimetrazine at a glance: schedule, half-life, and class
- Generic name
- Phendimetrazine tartrate
- Brand names
- Bontril PDM, Bontril SR (discontinued brands)
- Drug class
- Sympathomimetic amine (anorectic)
- US legal status
- Schedule III, prescription only
- Approved uses
- Short-term (a few weeks) management of exogenous obesity, BMI 30 or more
- Forms
- 35 mg tablets; 105 mg extended-release capsules
- Onset
- About 1 hour
- Active metabolite
- Phenmetrazine
Phendimetrazine uses: what it is used for
Phendimetrazine reduces appetite and is approved for a few weeks of use as part of a weight-loss program in people with a body mass index of 30 or more.[1]
Its effect on weight is modest and fades as tolerance develops. Newer medicines such as GLP-1 drugs are now used far more for long-term weight management.
Phendimetrazine dosage: how it is usually prescribed
The figures below come from the FDA-approved label and describe how prescribers typically use phendimetrazine. They are not personal dosing advice. A prescriber sets the dose for each person and adjusts it over time.[1]
| Product | Typical adult dose | Notes from the label |
|---|---|---|
| Immediate-release tablets | 35 mg two or three times a day, 1 hour before meals | Maximum 70 mg three times a day |
| Extended-release capsules | 105 mg once in the morning | 30 to 60 minutes before breakfast |
| Duration | A few weeks | Stop if no weight loss within 4 weeks |
Phendimetrazine side effects and risks
Common side effects include restlessness, insomnia, dry mouth, fast heartbeat, and raised blood pressure.[1]
Heart and lungs: appetite-suppressant stimulants raise heart rate and blood pressure. Rare but serious risks include pulmonary arterial hypertension and heart valve disease, especially when combined with other weight-loss drugs.[1]
Dependence: they are chemically related to amphetamine and can be misused; tolerance to the appetite effect develops within weeks.
Phendimetrazine interactions: what not to mix with it
Choose what it would be combined with:
| Combined with | What happens | Label guidance |
|---|---|---|
| MAO inhibitors (within 14 days) | Hypertensive crisis | Contraindicated |
| Other weight-loss drugs and stimulants | Heart and lung risks; overstimulation | Do not combine |
| Alcohol | Dizziness and masked impairment | Avoid |
| Insulin and diabetes medicines | Lower blood sugar as appetite falls | Dose adjustment may be needed |
| Blood pressure medicines | Reduced effect | Monitor |
This is not a full list. A pharmacist can check a complete medication list, including supplements and over-the-counter products.[1]
Phendimetrazine overdose: signs and what to do
Overdose causes restlessness, tremor, rapid breathing, confusion, aggression, hallucinations, high blood pressure, and abnormal heart rhythms, followed by fatigue and depression.[1]
If someone may be overdosing
- Call 911 for chest pain, a seizure, trouble breathing, signs of a stroke (face drooping, weakness on one side, slurred speech), a very high body temperature, or if the person collapses.
- Move them somewhere cool and calm, loosen tight clothing, and cool the skin with water. Do not try to hold them down.
- If they become unresponsive or their breathing slows, give naloxone. Street stimulants are often contaminated with fentanyl.
- For advice when the person is awake and stable, call Poison Help at 1-800-222-1222.
Phendimetrazine withdrawal timeline: symptoms and how long it lasts
Stopping phendimetrazine after regular use does not cause dangerous physical withdrawal, but it can cause a temporary crash.[1]
- Days 1 to 3CrashTiredness, increased sleep, hunger, and low mood.
- Week 1AdjustingLow energy, poor concentration, and irritability.
- Weeks 2 to 4SettlesMood and energy usually return to baseline.
Low mood after stopping can be significant. Anyone with thoughts of self-harm should call or text 988.
How to get prescribed phendimetrazine legally in the US
In the United States, phendimetrazine is a Schedule III controlled substance. The only legal way to get it is with a prescription from a clinician registered with the Drug Enforcement Administration (DEA), filled by a licensed pharmacy. Depending on state law, that can be a physician, nurse practitioner, or physician assistant.[2]
- Refills: a Schedule III prescription can be refilled up to five times within six months of the date it was written. After that, a new prescription is needed.[3]
- Telehealth: federal flexibilities let DEA-registered clinicians prescribe Schedule II to V medicines after a telemedicine visit, without a prior in-person exam, through December 31, 2026. A permanent DEA rule was under final review in late 2026. State rules can be stricter.[4]
- Monitoring: prescribers and pharmacists in most states check a prescription drug monitoring program, a database of controlled-substance prescriptions, before prescribing or dispensing.
- Pharmacies: a legitimate pharmacy always requires a valid prescription, has a licensed pharmacist available, and is licensed in the state it ships to. The FDA's BeSafeRx tool and the NABP's safe pharmacy list help confirm a pharmacy is real.[5][6]
- Cost: generic phendimetrazine is inexpensive but rarely covered for weight loss.
Traveling: keep the medicine in its original pharmacy container and carry a copy of the prescription. Check the rules of the destination country before travel, because many countries restrict controlled medicines or require a permit.
Can you order phendimetrazine online legally?
Yes, but only with a valid prescription and only from a pharmacy licensed in your state. Many licensed pharmacies, including mail-order pharmacies run by insurers, fill phendimetrazine prescriptions online and ship them. Buying phendimetrazine from a website that does not require a prescription is illegal, and the product is often fake.[5][7]
- See a licensed clinicianA clinician evaluates you in person or by telemedicine and decides whether phendimetrazine is appropriate.
- The prescription goes to a pharmacyPrescriptions are usually sent electronically, straight from the prescriber to the pharmacy you choose.
- The pharmacy checks and fills itA pharmacist verifies the prescription and your identity, then dispenses the medicine in person or by mail.
Signs that an online seller is illegal:
- It sells phendimetrazine with no prescription, or after only a short online questionnaire.
- It takes orders through social media, messaging apps, or email.
- It asks for payment in cryptocurrency, gift cards, or money transfers.
- It has no US street address, no state pharmacy license, and no pharmacist to speak to.
- Its prices are far below those of ordinary pharmacies, or it ships from another country.
The FDA's BeSafeRx tool links to each state's license lookup, and the National Association of Boards of Pharmacy lists verified online pharmacies.[5][6]
Phendimetrazine price: how much does phendimetrazine cost without insurance?
Generic phendimetrazine is inexpensive but rarely covered for weight loss.
What you pay depends on the strength, the number of doses, your insurance plan, and the pharmacy. Cash prices for the same prescription can differ several times over between pharmacies in the same town, so check current prices before you fill it.
Ways to pay less, legally:
- Ask the prescriber whether a generic phendimetrazine is available. FDA-approved generics work the same way as the brand and usually cost much less.
- Compare cash prices between pharmacies before you fill the prescription.
- Use a free prescription discount card, such as GoodRx or SingleCare, when you pay cash. These cards cannot be combined with insurance on the same fill.
- For brand-name medicines, check the manufacturer's savings program or patient assistance program.
- Ask about a 90-day supply or your insurer's mail-order pharmacy, which often lowers the cost per dose when your prescriber agrees it is appropriate.
Warning: A price far below what licensed pharmacies charge, especially with no prescription required, is a strong sign of an illegal seller and counterfeit medicine.[5]
Phendimetrazine legal status in other countries
| Country | Status |
|---|---|
| International | Schedule IV of the 1971 Convention on Psychotropic Substances |
Laws change and differ in detail. Check current rules before carrying any controlled medicine across a border.[8]
Common questions about phendimetrazine
Is phendimetrazine like phentermine?
Yes. Both are amphetamine-related appetite suppressants for short-term use.
How much weight can you lose on phendimetrazine?
Average extra weight loss in trials was modest, a few pounds over a few weeks.
Is phendimetrazine addictive?
It can be misused and cause dependence; it is a Schedule III controlled substance.
Can phendimetrazine be combined with phentermine?
No. Combining appetite suppressants raises heart and lung risks.
How long can I take phendimetrazine?
It is approved for a few weeks.
Can you buy phendimetrazine without a prescription?
No. phendimetrazine is a Schedule III controlled substance in the US, so it is illegal to buy or possess it without a valid prescription. Websites and social media sellers that offer it without one are not legal pharmacies, and the DEA warns that pills sold this way are often counterfeit and can contain fentanyl. The legal route is a visit with a licensed clinician, in person or by telehealth, and a prescription filled at a state-licensed pharmacy. The FDA's BeSafeRx tool and the NABP's safe pharmacy list help confirm an online pharmacy is real.
Sources
- Bontril (phendimetrazine) prescription information. DailyMed, US National Library of Medicine.
- Controlled Substance Schedules. DEA Diversion Control Division.
- 21 CFR 1306.22, Refilling of prescriptions (Schedules III and IV). Electronic Code of Federal Regulations.
- Prescribing controlled substances via telehealth. US Department of Health and Human Services.
- BeSafeRx: Your Source for Online Pharmacy Information. US Food and Drug Administration.
- Safe Pharmacy. National Association of Boards of Pharmacy.
- One Pill Can Kill. US Drug Enforcement Administration.
- International drug control conventions. United Nations Office on Drugs and Crime.
