Phentermine and Alcohol

Phentermine and Alcohol: A Dangerous Combination

Combining phentermine with alcohol can lead to severe side effects, including gastrointestinal problems, cardiovascular complications, and impaired judgment. It’s strongly recommended to abstain from alcohol while on phentermine to ensure both the efficacy of the weight loss medication and to avoid potential health risks.

Phentermine and Alcohol

Too busy for the full read? Here’s what you need to know:

  • It is strongly advised to abstain from alcohol while taking phentermine.
  • Drinking alcohol while on phentermine treatment may lower the chances of successful weight loss and increases the risk of unpleasant side effects.
  • The mixture of phentermine and alcohol can worsen gastrointestinal symptoms, such as nausea, stomach pain, diarrhea, and constipation.
  • Cardiovascular complications, including a significant increase in heart rate or blood pressure, can occur when combining phentermine and alcohol.
  • Mixing phentermine and alcohol can impair judgment, impact balance, communication, memory, and speech due to their effects on the central nervous system.

Phentermine is a diet pill that is commonly prescribed to aid weight loss. It is a central nervous system stimulant that suppresses the appetite and boosts energy levels. You may recognize phentermine by its brand names, such as Adipex (Adipex-P), Qsymia, or Lomaira. (1)

Phentermine is a popular drug, but like most medications, it also has risks and side effects. These risks can be increased when mixing alcohol and phentermine.

Can You Drink Alcohol While Taking Phentermine?

If you are taking phentermine, the best advice is to abstain from drinking alcohol. This is because phentermine and alcohol can interact.

Furthermore, if you drink alcohol while taking phentermine, your chance of losing weight may be lower.

Phentermine is usually only prescribed for 12 weeks at a time, so where possible, it is best to abstain during this short period. (2)

Phentermine and Alcohol: Side Effects

Although phentermine is popular, it commonly causes unwanted and unpleasant side effects even when taken as directed. This includes a dry mouth, hair loss, and acne.

However, phentermine can also cause more serious adverse health outcomes, including changes to the normal heart rhythm. When phentermine is mixed with alcohol, the serious side effects of phentermine can be aggravated.

For this reason, phentermine is unlikely to be a safe choice if you drink regularly, have an addiction to alcohol, experience alcohol cravings, or do not want to abstain from alcohol while taking phentermine.

Gastrointestinal Problems

Common side effects of phentermine include nausea, stomach pain, diarrhea, and constipation.

Regularly drinking alcohol is also known to cause acid reflux. This is because alcohol irritates the lining of the stomach and digestive tract.

Taking phentermine with alcohol increases the risk that these unpleasant digestive symptoms will occur or worsen. (3)

Cardiovascular Side Effects

One of the most severe risks of taking phentermine is a significant heart rate or blood pressure increase, even if you have never previously had heart or blood vessel disease. Individuals with underlying heart disease are at greater risk and may therefore be advised that phentermine will not suit them.

Drinking alcohol when taking phentermine can increase the risk of cardiovascular complications occurring.

In rare cases, there is a risk of stroke or fatal heart disease. Those who experience symptoms must seek immediate medical advice. (4)

Central Nervous System (CNS) Effects

Combining phentermine and alcohol may lead to difficulty concentrating.

Alcohol is known to impact the pathways in the brain needed for balance, communication, memory, speech, and judgment. Phentermine and alcohol side effects include dizziness or drowsiness.

You may also find that your judgment is significantly more impaired than when taking phentermine or alcohol alone. This decrease could have a negative impact on your ability to work or make rational decisions. (5)

Adverse Effects on Weight Loss

Phentermine and alcohol interaction should be avoided for the above health reasons. However, it is also important to remember that combining alcohol with generic phentermine or Adipex may prevent weight loss.

While phentermine boosts the central nervous system to increase energy, alcohol suppresses it.

Alcohol is likely to reduce your drive to exercise. You may also be less likely to make healthy food choices when intoxicated. You could consume fatty or sugary foods that will cause weight gain rather than loss. Finally, alcohol itself is calorie rich.

In summary, drinking alcohol may undo the hard work you put into losing weight with phentermine.


Phentermine is a popular weight loss medication that stimulates the central nervous system. However, when taken together, phentermine and alcohol can cause unpleasant digestive side effects, worrying cardiovascular symptoms, and reduce your ability to make rational decisions.

Furthermore, drinking alcohol can reduce how effective phentermine is at aiding weight loss.

Phentermine should, therefore, only be taken by individuals who can abstain from alcohol during the treatment course.


Why can’t you have alcohol with phentermine?

Mixing alcohol and phentermine can increase the risk of side effects, including nausea or diarrhea, and cause health complications such as high blood pressure and a rapid heartbeat. It may also impair your judgment. Alcohol is calorie dense, and you may, therefore, also find it harder to lose weight if you drink.

What effects does alcohol have on phentermine?

Drinking alcohol can make phentermine less effective. It may also increase the chance you will experience serious interactions.

Does alcohol reduce the effectiveness of phentermine?

Yes, alcohol will reduce your chance of losing weight with phentermine. Alcohol is calorie-dense and is, therefore, likely to lead to weight gain.

Alcohol is also a depressant, which may make you feel less motivated to exercise. You may find that your judgment is affected by alcohol, meaning you succumb to the desire to eat unhealthy foods that will prevent weight loss.

Does alcohol interfere with phentermine’s appetite-suppressing effects?

Yes, alcohol may counteract phentermine’s appetite-suppressing and energy-boosting effects. It may affect the central nervous system in a manner that potentially hinders your weight loss efforts.

How long after taking phentermine can I drink alcohol?

To avoid side effects, it is best to wait around 12 hours after taking phentermine before you drink alcohol.

Although it is best to avoid alcohol when taking phentermine altogether, there may be a rare occasion when you can accept a drink.

Can I drink alcohol 12 hours after taking phentermine?

Waiting 12 hours after your last dose of phentermine is advisable to avoid phentermine and alcohol side effects. However, it is best to avoid alcohol, if possible, entirely.

How long after you stop taking phentermine can you drink alcohol?

Once you have stopped taking phentermine, you can begin drinking alcohol again. It is best to wait two to three days for phentermine to completely clear from your system.

However, to maintain weight loss, limit how much you drink, as alcohol can quickly cause weight gain.

What happens if you drink alcohol while taking phentermine?

When phentermine is mixed with alcohol, you are more likely to experience side effects such as a racing heartbeat, high blood pressure, problems concentrating or making decisions, and drowsiness.

You may also make decisions that you would not usually make. It is, therefore, safer to avoid alcohol when taking phentermine.

How much alcohol can you drink with phentermine?

It is best to avoid alcohol when taking phentermine or Adipex. However, if you want to drink at a special occasion or event, you may choose to have one or two drinks as long as at least 12 hours have passed since you last took a dose of phentermine.

Can you drink wine with phentermine?

Drinking wine with phentermine will increase the risk of side effects. A large glass of white wine (250ml) contains around 190 calories. Drinking wine is, therefore, also likely to prevent you from losing weight and may even lead to weight gain. (6)

Can you drink beer with phentermine?

Drinking beer when taking phentermine may increase the risk of adverse health events. A pint of beer contains around 180 calories. Regularly drinking is, therefore, likely to lead to weight gain. (7)


1. (Phentermine)
2. (What is Phentermine).
3. (Gastrointestinal Side Effects)
4. (Phentermine and Alcohol).
5. (Alcohol and the Brain).
6. (Wine Calories).
7. (Beer Calories).