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One of the most important things to do when you get a new medication is to research the known interactions for that medication. 

Knowing what you’re taking, why you’re taking it, and what your medications can interact with is a basic form of safety you can use to ensure you’re safe and that you aren’t at risk of health complications you don’t know about. 

Unfortunately, since alcohol is commonly accepted in our society, many people don’t realize that alcohol can interact with medications and cause problems. 

Phentermine is a prescription drug, but that doesn’t mean that phentermine and alcohol are safe together. Here’s what you need to know about phentermine and alcohol and why using phentermine and alcohol together can indicate a more serious problem. 

This information is designed to be helpful whether you’re taking phentermine yourself or researching the drug to get more information because a friend or family member has started taking it. 


Let’s go! 

What Is Phentermine?

The first thing you need to know about phentermine and alcohol is what phentermine is. 

Phentermine is a prescription drug to help with weight loss, exercise, a reduced-calorie diet, and lifestyle changes. One way phentermine works is by reducing your feelings of hunger, which makes it easier to stick to a diet or avoid binge eating, and can help overcome your body’s natural reaction to early weight loss. 

Generally, this drug only has mild side effects. However, your doctor should still evaluate you to ensure the potential benefits of the prescription outweigh the potential downsides of side effects or risks. 

Common side effects of phentermine include: 

  • Dizziness
  • Dry mouth
  • Insomnia
  • Hair loss
  • Acne
  • Nausea
  • Vomiting
  • Diarrhea
  • Constipation
  • Increased blood pressure

Other side effects, like abnormal heart rate, severe headaches, seizures, or hallucinations, should be reported to your doctor immediately. Depending on your symptoms, pre-existing health, and the severity of the side effect, you may be directed to your local emergency room if you have more serious side effects. 

The Dangers Of Mixing Phentermine And Alcohol

If you’re familiar with the common side effects of alcohol, you may have already spotted one problem with mixing phentermine and alcohol. Alcohol and phentermine can both increase your blood pressure. Taking too many drugs that increase blood pressure is dangerous, even if your normal blood pressure is in the healthy range. 

However, high blood pressure isn’t the only risk of mixing phentermine and alcohol. 

Alcohol causes many dangerous side effects when mixed with phentermine. For several reasons, alcohol can also diminish phentermine effects. Alcoholic beverages are usually high-calorie, and the effects of alcohol can counteract the beneficial effects of phentermine. 

That means more risks and fewer benefits when you mix alcohol with phentermine. 

Additionally, alcohol is known to increase the severity of side effects from phentermine. It can sometimes increase the side effects so severely that you start getting side effects you wouldn’t have had from phentermine alone. 

For instance, since both alcohol and phentermine can increase your heart rate and blood pressure, the combination can increase the risk of a stroke or seizure. You may also be at increased risk of heart problems because the drugs work together and compound each other’s effects. 

Phentermine and alcohol can also work on your gastrointestinal tract, causing nausea, vomiting, constipation, and diarrhea, depending on how your body processes the drugs, how much you take, and which symptoms you’re most susceptible to. 

You may also be at increased risk of acid reflux or heartburn from these drugs. 

Lastly, combining phentermine and alcohol can affect your central nervous system, making concentrating difficult. Both phentermine and alcohol can make you dizzy or make you disoriented. Combined, you may also notice that it’s harder to make decisions or behave rationally than with either drug alone. 

Combining alcohol and diet pills can lead to increased side effects from both drugs

Can You Drink Alcohol With Diet Pills? 

Generally, no. While not all diet pills interact with alcohol, many do.  

Combining alcohol and drugs can lead to increased side effects from both drugs. For example, you may be at increased risk of depression, difficulty concentrating, dangerous heart problems, dizziness, and other problems. 

If you have diabetes or are at risk of developing diabetes, you may also have more severe reactions to combining diet pills and alcohol, and alcohol usually isn’t a good idea with diabetes anyway. 

Lastly, combining many diet pills with alcohol can increase your risk of seizures, whether you have a pre-existing seizure disorder. 

How Long Is Phentermine In Your System? 

Phentermine comes in several different formulations, and you may have to take several doses throughout the day to be effective. 

That doesn’t mean that phentermine is completely out of your system if you skip a dose, and skipping so that you can drink usually isn’t a good idea either. 

That’s because the phentermine usually doesn’t leave your system immediately. Instead, you may need more to stop yourself from getting below an effective active dose before mealtimes. 

Because phentermine is usually prescribed for about 12 weeks, it’s important to ensure you aren’t drinking while taking phentermine or generally for a few days after stopping. That way, you can minimize your risk of interactions between phentermine and alcohol and get the full weight loss benefit of the phentermine. 

Signs Of Addiction

Many potential signs of addiction exist, and the inability to abstain from alcohol while taking a phentermine prescription indicates that you might be dealing with an addiction. 

Here are some other common signs of addiction that can be used to help identify addiction to drugs and alcohol.

  • You feel distracted by cravings for drugs or alcohol
  • You think about when you’ll be able to get more drugs or alcohol when you’re sober
  • You have or have been tempted to use drugs or alcohol at work or school
  • You feel like you have to hide how you use drugs or alcohol from the people close to you
  • You have struggled with your budget as a result of using drugs or alcohol
  • You have or have considered stealing things to fund getting more drugs or alcohol
  • You feel like you need to use drugs to alcohol to be your true self
  • You feel like using drugs or alcohol to help you express yourself
  • You feel depressed or anxious when you can’t use drugs or alcohol
  • You have considered using drugs or alcohol to cope with high-stress situations
  • You feel like you need to use drugs or alcohol every day or multiple times a day
  • You worry about what would happen if you can’t access drugs or alcohol

These are some of the general feeling that can come with addiction.

Frequently Asked Questions About Phentermine And Alcohol

There are a lot of questions about phentermine and alcohol, so don’t feel bad if you have some of these questions or even more. Here are some of the most frequently asked questions about phentermine and alcohol so you can be better prepared if you are ever prescribed this medication. 

Do You Feel High On Phentermine? 

Yes, phentermine can give some users a euphoric or high feeling, but that isn’t the goal. Additionally, it might even be a good reason to switch medications if that high feeling makes it difficult to function normally while taking the medication. 

Remember, phentermine isn’t supposed to be a medication you only take in the evenings or while you’re able to be off work for a few days. You’re supposed to be on this medication for a few weeks at a time, meaning most people need to function normally while taking phentermine. 

Is Phentermine Addictive? 

When phentermine is used properly for treating obesity, it isn’t typically addictive. However, that doesn’t mean there isn’t a risk of dependence or addiction when the medication is abused or when patients take more than prescribed. 

Is phentermine addictive?

What Happens If You Drink With Phentermine? 

Everyone’s reaction to drinking while on phentermine might be slightly different, but it’s never safe. The main risks of drinking while on phentermine are high blood pressure, heart problems, and additional complications from those issues, but you may also have worse side effects than usual from the alcohol if you drink while on phentermine.

How To Get Addiction Help

If you suspect that you or someone you love might be dealing with an addiction, it’s important to get qualified help as soon as possible. The earlier in addiction you can intervene and get help, the more successful addiction treatment is likely to be. 

One option is to talk to your primary care doctor about your concerns and ask what local resources are available to deal with addiction. 

But, if you’re looking for more comprehensive help or need addiction treatment that can also manage obesity or other chronic health conditions at the same time, you might be better served by going straight to an addiction treatment center. 

If addiction treatment centers, where you have access to care 24/7, and high-quality science-driven therapies, sound like the best option to you, contact Absolute Awakenings. We’re here to help you overcome and see what life can look like when you put addiction in the rear-view window.


  1. England H. Phentermine and Alcohol: A Dangerous Combination – Published November 25, 2022. Accessed January 11, 2023.
  2. Perlowski A. Does Alcohol Raise or Lower Blood Pressure? Find Out Here – GoodRx. Published July 28, 2022. Accessed January 11, 2023.
  3. Can You Mix Weight Loss Drugs and Alcohol? Published June 8, 2021. Accessed January 11, 2023.
  4. Niel T. 9 Phentermine Side Effects You Should Know About. GoodRx. Published October 20, 2022. Accessed January 11, 2023.
  5. Hendricks EJ, Srisurapanont M, Schmidt SL, et al. Addiction potential of phentermine prescribed during long-term treatment of obesity. Int J Obes (Lond). 2014;38(2):292-298. doi:10.1038/ijo.2013.74

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At Absolute Awakenings, we take information integrity seriously. We have dedicated our resources to ensure that all content published to our blog is medically sound. As such, all content on our blog has been thoroughly reviewed by a doctorate level clinician such as a Medical Doctor, or Psy.D, so that you can trust all of the data we publish.

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