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Medicine & Alcohol

can i drink alcohol 12 hours after taking phentermine

Quick answer

We found no official page that gives a number of hours. MedlinePlus says to ask your doctor about the safe use of alcohol while taking phentermine and that alcohol can make its side effects worse. Phentermine is usually taken once in the morning or up to three times a day.

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In this article
  1. What MedlinePlus says
  2. Dosing matters
  3. Side effects to watch
  4. What to do

What MedlinePlus says

For phentermine, an appetite suppressant used for short-term weight loss, MedlinePlus says: “Alcohol can make the side effects of phentermine worse,” and to ask your doctor about the safe use of alcohol while taking it. It does not give a waiting time.

Dosing matters

The page says phentermine “usually is taken as a single daily dose in the morning or three times a day 30 minutes before meals,” and most people take it for 3 to 6 weeks. If you are still on the drug, a drink 12 hours after a dose is still during treatment, which is our reading. Extended-release tablets should not be split, chewed or crushed.

Side effects to watch

Mild effects include dry mouth, unpleasant taste, diarrhea, constipation and vomiting. Call your doctor right away for increased blood pressure, heart palpitations, chest pain or shortness of breath. The page also says not to drive until you know how it affects you.

What to do

Ask your pharmacist for advice on your dose and timing. This is general information, not medical advice.

People also ask

Can you drink alcohol while taking phentermine?

MedlinePlus says alcohol can make its side effects worse and to ask your doctor about safe use.

How long does phentermine treatment last?

MedlinePlus says most people take it for 3 to 6 weeks, depending on response.

What serious side effects need a doctor?

Increased blood pressure, heart palpitations, chest pain and shortness of breath, according to MedlinePlus.

General information only, not medical or legal advice. If you have a health condition, take medicines or are pregnant, ask your doctor before drinking alcohol. Never drink and drive.

Sources

  1. MedlinePlus (NLM): Phentermine, read 4 Nov 2026
  2. NIAAA (NIH): Harmful Interactions, Mixing Alcohol with Medicines, read 4 Nov 2026
Written by A to Z Alcohol Editorial Team · Published Sep 27, 2024 · Updated Nov 4, 2026
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