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Medically Reviewed

Can You Mix Phentermine and Alcohol?

- 8 sections

Medically Reviewed: September 20, 2023

Medical Reviewer

Sahil Talwar, PA-C, MBA


All of the information on this page has been reviewed and verified by a certified addiction professional.

Alcohol is a big part of American society, so much so that you can find people drinking in almost every setting. According to the National Institute of Alcohol Abuse and Alcoholism (NIAAA), nearly 80% of people aged 12 or older reported drinking at least once in their lifetime.[1]

While occasional alcohol use is fine, sometimes people forget to check whether their medications interact negatively with alcohol. Even certain over-the-counter medications can cause damaging effects when mixed with alcohol. However, when you are on prescription medication, you must ensure it is safe to mix with alcohol before drinking.

One of the prescription medications you should never mix with alcohol is phentermine (Adipex-P or Lomaira). If you are currently taking this substance it is important to be aware of the potential interactions you could experience.

What is Phentermine?

Phentermine is a prescription medication intended for weight loss that might be referred to as Adipex-P or Lomaira. When taken for weight loss, phentermine works by making you feel less hungry or keeping you feeling full longer. While this medication can be abused, it is only considered a Schedule 4 drug because misuse is not common.

Because phentermine is a stimulant, it can speed up messages between your brain and body. This can cause you to feel energized and lead to increased heart or breathing rates. Due to its stimulant effects, phentermine can cause addiction when it is misused.

The common side effects of phentermine include:[2]

  • Dry mouth
  • Unpleasant taste in the mouth
  • Diarrhea
  • Constipation
  • Nausea and vomiting

Phentermine can also lead to severe side effects that require medical intervention when someone is allergic or takes too much of the medication. These side-effects include:[2]

  • Increased blood pressure
  • Heart palpitations
  • Restlessness and tremors
  • Dizziness
  • Insomnia
  • Shortness of breath
  • Chest pain
  • Swelling of the ankles and legs
  • Difficulty engaging in exercise that used to be tolerable

What are the Dangers of Mixing Phentermine and Alcohol?

Phentermine should never be taken with alcohol. When you mix phentermine and alcohol, you can experience potentially life-threatening effects that require immediate medical treatment.

Some of the dangers associated with combining phentermine and alcohol include:

Gastrointestinal Issues

When you mix phentermine and alcohol you can experience gastrointestinal issues because of the way that alcohol irritates the lining of your stomach.

Gastrointestinal issues related to combining alcohol and phentermine include:[3]

  • Heartburn
  • Stomach aches and pains
  • Nausea and vomiting

Cardiovascular Risks

Phentermine is considered a stimulant, and combining stimulants with alcohol can lead to damaging cardiovascular problems. This is one of the many reasons you should never mix the two substances.

The cardiovascular concerns associated with mixing alcohol and phentermine include:[3]

  • Increased heart rate and palpitations
  • Chest pain
  • Increases in blood pressure
  • Heart failure among individuals with pre-existing heart conditions

Central Nervous System Effects

Lastly, phentermine is a stimulant while alcohol is a depressant. Mixing a depressant and stimulant drug can confuse the central nervous system, leading to dangerous effects.

The effects combining alcohol and phentermine can have on the central nervous system include:[3]

  • Dizziness
  • Severe drowsiness
  • Difficulty concentrating
  • Mental confusion
  • Increased symptoms of depression or suicidal ideation


Oftentimes, alcohol can make you feel like stimulant substances like phentermine are not affecting you, causing you to take more of the medication than your body can handle, potentially leading to an overdose.

The symptoms of a phentermine overdose include:[3]

  • Mental confusion
  • Anxiety or panic
  • Nausea and vomiting
  • Hallucinations
  • Diarrhea
  • Stomach cramps
  • Depression and extreme tiredness
  • Irregular heartbeat
  • Weakened pulse
  • Slowed or stopped breathing
  • Seizures

Phentermine overdose can be life-threatening, so you should always contact 911 immediately when you suspect an overdose.

How Long Should You Wait to Drink Alcohol?

If you are going to drink alcohol, you must wait until your phentermine is no longer affecting you. Because the half-life of phentermine is about 20 hours, it is not safe to drink alcohol on the same day that you consumed the medication.[4] In other words, alcohol consumption is not safe while you are actively taking alcohol.

Individuals who suffer from an alcohol use disorder must consult with their doctor about whether it is safe for them to start taking phentermine for weight loss. In most cases, your doctor will ask you to receive treatment for your alcoholism before you begin phentermine treatment.

Find Help for Alcohol Abuse and Addiction

If you or a loved one suffer from alcoholism, it’s time to seek help. Not only can alcohol use disorder cause devastating effects on your health, but it also prevents you from taking weight loss medications like phentermine.

At Charlotte Detox Center, our alcohol detox center can provide you with the support and treatment you need to overcome alcohol withdrawal. To learn more about how we can help, contact us today.


  1. The National Institute of Alcohol Abuse and Alcoholism (NIAAA): Alcohol Use in the United States, Retrieved September 2023 From
  2. Medline Plus: Phentermine, Retrieved September 2023 From
  3. The Food and Drug Administration (FDA): Adipex-p (phentermine hydrochloride), Retrieved September 2023 From
  4. The National Library of Medicine (NLM): Topiramate and Phentermine, Retrieved September 2023 From