Key takeaways:
Phentermine (Adipex-P) is a prescription weight-loss medication. It’s also an active ingredient in another weight-loss medication called Qsymia (phentermine / topiramate).
Alcohol can make some phentermine side effects worse. And phentermine can make you more sensitive to alcohol and increase your risk of alcohol-related harm.
Alcohol can interfere with your weight loss goals. And it can also be harmful to your overall health and wellness.
For some people, dietary changes and regular exercise may not be enough to achieve their health and wellness goals. That’s where weight-loss medications such as phentermine (Adipex-P) come into play. Phentermine is an oral tablet your healthcare provider may prescribe to help you lose weight. It’s also one of the active ingredients — along with topiramate — in the medication Qsymia.
Phentermine works best in combination with exercise and a reduced-calorie diet. But can you drink alcohol while you’re taking it? Here, we’ll look at the main reasons why alcohol and phentermine are a combination that’s best to avoid.
1. Alcohol may worsen phentermine side effects
Phentermine helps reduce your appetite, and it may boost your metabolism, too. But, like any medication, it has some side effects. And these side effects may be worsened by alcohol. Phentermine and alcohol can both cause:
Dizziness
Headache
Increased blood pressure and heart rate
An altered mental state
Dependence and misuse
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When you combine phentermine and alcohol, the risk for these side effects may go up. The prescribing information for phentermine includes a warning that alcohol can cause a negative reaction to the medication. The best way to prevent this is to avoid alcohol while you’re taking phentermine.
2. Phentermine’s effects may make you more sensitive to alcohol
As mentioned, phentermine reduces your appetite, which means you’ll likely eat less food than you usually do while you’re taking it. This can change the way alcohol is absorbed. The less you eat, the faster you’ll absorb alcohol.
In addition, phentermine is a stimulant medication. Its energizing effect may mask the symptoms of alcohol intoxication. This can make it harder to tell how intoxicated or impaired you are while drinking. It can also cause you to drink more alcohol than you normally would.
Because of this, you may get intoxicated faster and more intensely if you mix alcohol and phentermine. This increased sensitivity can put you at a higher risk of alcohol-related harm, including accidents, injuries, and poor decision making.
Is having 1 or 2 drinks OK?
There isn’t any amount of alcohol that’s completely safe to drink with phentermine. That being said, the more alcohol you drink, the more likely you are to have negative effects from the combination. And everyone responds to the effects of alcohol and medications differently, too.
Keep in mind that alcohol can also be a problem if you combine it with other health conditions and medications. So it’s best to talk to your healthcare provider about whether an occasional alcoholic beverage is OK for you while you’re taking phentermine.
3. Alcohol can interfere with your weight loss goals
Alcohol is high in empty calories that can undermine the weight-loss benefits of phentermine. And it’s often mixed with other high-calorie liquids, such as fruit juice or soft drinks.
Drinking alcohol can also stimulate your appetite. And often, food choices made under the influence of alcohol aren’t the most nutritious options. What’s more, alcohol can slow down your metabolism and keep your body from burning fat. This is what causes some people to develop a so-called “beer belly.”
How long after taking phentermine should you wait before having a drink?
Phentermine can stay in your system for around 4 days, sometimes longer. So it’s best to wait at least 4 days after your last dose of phentermine before having a drink.
Even after you stop taking phentermine, remember that regular alcohol consumption can still interfere with your health and wellness goals. There’s not a set amount of alcohol that’s considered safe. But the CDC recommends no more than 2 drinks for men and 1 drink for women per day on the days you choose to have it to reduce the risk of harm.
Are there are any weight loss medications that aren’t affected by alcohol?
Not really. Alcohol can interfere with your weight-loss goals and affect your overall health regardless of which weight-loss medication you’re taking. But other weight-loss medications may be a safer option than phentermine if you drink alcohol regularly.
GLP-1 agonists, such as semaglutide (Wegovy, Ozempic, Rybelsus) are medications approved for diabetes and/or weight loss. There’s no direct interaction between alcohol and GLP1 agonists. But combining them can increase your risk of side effects, such as nausea, vomiting, and diarrhea. That being said, people have reported that GLP-1 agonists decrease their desire to drink alcohol. So these medications may be a better option for you if you consume alcohol regularly.
Orlistat (Alli) is a weight-loss medication that keeps your body from absorbing the fat in your meals. Orlistat also does not directly interact with alcohol. But common side effects of this medication include diarrhea and oily or fatty feces, which alcohol may worsen.
While these medications may be less likely to interact with alcohol, it’s best to talk to your healthcare provider about the right weight-loss medication for your needs. Remember that being honest about how much alcohol you drink can help them give you the safest options. They can also provide resources to help you cut back or stop drinking.
The bottom line
It’s best to avoid alcohol while taking phentermine (Adipex-P) for weight loss. Alcohol may make phentermine’s side effects worse. And phentermine can make you more sensitive to alcohol’s effects. Alcohol can also be harmful to your health and interfere with your weight-loss goals.
If you consume alcohol regularly, a different weight-loss medication may be a better option for you. Talking openly with your healthcare provider about how much alcohol you drink can help them protect your safety. They can give you medications options that aren’t as risky and provide support to help you cut back or stop drinking if needed.
Why trust our experts?
If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-4357 to learn about resources in your area.
References
Centers for Disease Control and Prevention. (2022). Dietary guidelines for alcohol.
Centers for Disease Control and Prevention. (2022). Polysubstance use facts.
Direct Rx. (2023). Phentermine hydrochloride [package insert].
Kase, C. A., et al. (2017). The relationship of alcohol use to weight loss in the context of behavioral weight loss treatment. Appetite.
National Center for Biotechnology Information. (2023). Compound summary: Phentermine. National Library of Medicine.
Wilson, D. F., et al. (2020). Ethanol metabolism: The good, the bad, and the ugly. Medical Hypothesis.
World Health Organization. (2022). Alcohol.
Yeomans, M. R., et al. (2003). Alcohol and food intake. Current Opinion in Clinical Nutrition and Metabolic Care.
