What Will Happen If You Mix Phentermine and Alcohol?

by Marixie Ann Obsioma, MT, undergrad MD on January 2, 2019
Last updated on May 23, 2021

Losing excess fat and keeping it off is easier said than done, especially for those who love to drink alcohol.

a glass of ice and alcohol

If you are one of the 1.9 billion adults who are classified as either overweight or obese, you know this challenge all too well (1).

Recreational drinking is a widespread activity worldwide and alcohol can cause weight gain if not compensated for.

Being overweight or obese do not just lower your self-confidence and esteem, it can also lead to serious health issues like heart diseases, high blood pressure, and type 2 diabetes (2).

Thankfully, you can reduce your risks by taking a weight loss supplement exactly as prescribed by a medical professional.

For sure, you have heard about Phentermine and its claims.

As will be explained in greater detail below, losing weight doesn’t happen overnight, but is weeks or months in the making.

There are several things to take into consideration for it to be effective and to avoid possible side effects.

What is Phentermine?

Phentermine is an amphetamine-like drug that can help suppress one’s appetite. It decreases your cravings and hunger and makes you feel full.

Though the exact mechanism of action is not yet fully understood, it is believed that Phentermine stimulates the neurons to produce dopamine and norepinephrine. These two can curb your appetite (3).

Similar to other weight loss drugs, Phentermine is intended to be used as an adjunct to diet and exercises.

It is classified as a Schedule IV drug, which has a potential for abuse (4).

How to use Phentermine?

Phentermine must only be taken with the supervision of a medical doctor. You must not take more than what is advised. As mentioned earlier, this drug has a potential for abuse. If you take more of it, drug dependence may develop.

Phentermine is available in different forms. Each one of them has their own dosing instructions.

Tablet and extended-release forms must be taken as a whole. Disintegrating tablets, on the other hand, must be placed on top of your tongue to be melted (5).

Phentermine, as a stimulant, must be taken early in the morning to avoid insomnia (6).

There are several other things to consider when taking Phentermine to avoid unwanted side effects.

One caution that must be given attention is the use of this drug with alcohol.

How Can Alcohol Affect Weight Loss?

We all love drinking alcohol, especially during social gatherings. While some studies suggest that it lower your risk for heart diseases, alcohol also plays a major role in weight reduction.

If you want to drop that excess fat, you should consider skipping your favorite glass of liquor.

There are several ways alcohol can interfere with your weight loss journey.

1. Alcoholic drinks are “empty” calories

Alcohol gives you calories with fewer amounts of nutrients.

A can of beer and a glass of red wine contains 155 and 125 calories, respectively. The recommended intake for an afternoon snack should only be between 150-200 calories (7).

Imagine a night out with several drinks. That gives you a few hundred excess calories and much more if your liquors are mixed with soda or fruit juices.

2. Alcohol as a source of body fuel

The body immediately burns alcohol for body fuel before other sources like carbohydrates, lipids, and fats (7).

If your body uses alcohol as its main source of energy, excess sugar and lipids end up as reserves in the form of fats.

3. Alcohol Affects Your Stomach, Kidneys, and Liver

Alcohol is a by-product of yeast digestion. It can irritate the stomach lining and gradually weaken the liver and kidneys (8).

Any weakening of the stomach will decrease the rate of food digestion, which ultimately affects weight loss.

The liver plays an important role in keeping a healthy body composition. It detoxifies our body.

Alcohol is most destructive during detoxification (8).

4. Alcohol can lower testosterone level

Alcohol reduces testosterone level, thus halting its fat burning effect.

Testosterone is an anabolic hormone. It contributes to gains in lean muscle mass. Without it, there will be fewer muscle gains and a decreased metabolic rate (8).

A low metabolic rate will make weight reduction a lot more difficult.

5. Alcohol reduces the quality of sleep

Everyone thinks that a glass of wine or beer before bedtime may sound like a ticket a long, deep sleep but you may want to reconsider.

One study shows that alcohol can increase periods of wakefulness during sleep cycles (9).

Lack of sleep or impaired sleep can cause hormonal imbalance related to cravings, hunger, and energy storage (7).

6. Alcohol causes poor decision making

It is tough to fight the urge to eat if you are intoxicated with alcohol.

Alcohol lowers inhibitions, and this may affect your judgment, especially with food choices.

A study on mice showed a significant increase in food intake among subjects that were given ethanol for 3 days (10).

Knowing that alcohol can alter the normal process of weight reduction, what will happen if you mix it with a weight loss drug like Phentermine? An interaction between Phentermine and alcohol

Mixing Phentermine and alcohol can cause dangerous side effects (11).

Phentermine is a stimulant while alcohol is a depressant. They have contrasting effects, which can cause an adverse drug interaction.

You may have an increased risk of the following:

Cardiovascular diseases

The combination of alcohol and Phentermine can increase your risk of cardiovascular diseases. You may experience chest pain, increased heart rate, and changes in blood pressure (11).

Drowsiness, dizziness, depression, and difficulty concentrating are also very common (11).


Another reason you must not take Phentermine and alcohol is that it increases your risk of addiction (12).

These two substances have the potential for abuse, and if you take them together, you’re more likely to develop dependence and addiction.


Alcohol can thin your blood and weight loss drugs can increase blood pressure.

Taking them together raises your risk of bleeding in case of an injury. Even a small wound on your skin can warrant an immediate trip to the ER (13).

Panic attacks

During a panic attack, your heart starts to pound harder and faster and you may feel dizzy or nauseous with an upset stomach. Alcohol can intensify these symptoms (13).

According to HelpGuide.org, diet pills may cause an onset of a panic attack because of its stimulatory effect (13).

By mixing alcohol and diet pills, you greatly increase your risk.

Your health is just too important not to invest in!


While it is okay to start your weight loss journey with Phentermine, it is something that you need to do with caution.

Refrain from drinking alcohol while on Phentermine treatment to avoid unwanted side effects.

To be successful in your weight loss journey, act in a way that you know is right for your body and well-being!


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