Adipex-P Results, Risks, Side Effects

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If you are thinking about taking a prescription diet pill, there are several medications that your doctor might prescribe. One of the most widely used weight loss medications is Adipex-P (phentermine hydrochloride). But just like every weight loss medication, there are Adipex side effects, contraindications, and lifestyle factors that you should consider before taking the pills.

What Is Adipex-P?

Adipex-P is the brand name for a medication called phentermine. Phentermine was approved by the Food and Drug Administration (FDA) in 1959. The medication works to decrease appetite and speed weight loss in people who are also following a low-calorie diet and exercise program.

Adipex is generally prescribed for people with a body mass index (BMI) of 30 or more or for those with a BMI of 27 or more and who also have a weight-related risk factor like diabetes, high cholesterol or controlled high blood pressure.

Adipex is generally prescribed for short-term weight loss, lasting less than 12 weeks. However, some studies acknowledge that the medication is often prescribed off-label for a longer duration.


Many patients who follow an Adipex-P weight loss plan take one 37.5 mg tablet or capsule in the morning before breakfast. But your doctor will recommend the best dose for you based on your personal health profile.


According to prescribing information for the medication, there are certain people who should not take Adipex-P. These include patients who:

  • Are allergic to sympathomimetic amines such as phentermine, or any of the ingredients
  • Are pregnant or are nursing
  • Are taking certain medicines called monoamine oxidase inhibitors (MAOIs) or have taken MAOIs in the past 14 days
  • Have a history of heart disease (such as coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled high blood pressure)
  • Have experienced agitated states or have a history of drug abuse
  • Have glaucoma (increased pressure in the eyes)
  • Have impaired kidney function or are on dialysis
  • Have thyroid problems (hyperthyroidism)

If you take Adipex-P, you should not consume alcohol and you should be aware that the medication may impair your ability to operate machinery or drive a motor vehicle. If you are on other weight loss medications, it is not recommended that you take Adipex-P.

Lastly, Adipex may cause an increase in blood pressure. So check with your health care team if you are being treated for hypertension. In patients with diabetes, it may also cause a decrease in the dose of insulin or other oral hypoglycemic medications that are required. Work together with your health care provider to make sure your condition is managed properly.

Side Effects

Those who take Adipex-P may experience side effects including depression, nervousness, problems sleeping, dry mouth, constipation, unpleasant taste, diarrhea or vomiting. Researchers studying the medication have reported that the most common side effects are dry mouth and insomnia.

Some patients taking Adipex-P may experience more serious problems including increased blood pressure, heart palpitations, dizziness, tremors, shortness of breath, chest pain, swelling of the legs and ankles or difficulty doing exercises that you can usually do.

You should contact your doctor immediately if you experience any decrease in the amount of exercise you are normally able to tolerate.

Prescribing information for the medication states that taking phentermine and phentermine-like products have been associated with primary pulmonary hypertension, a rare but often fatal disease of the lungs, so you should tell your health care provider if you have shortness of breath, chest or heart pain, or experience fainting or swelling in your lower legs. Lastly, there may be an association between phentermine and phentermine-like products and serious heart valve problems or disease.

Typical Results

According to the National Institutes of Health, the average weight loss for patients on medications like Adipex-P is approximately 5 to 10 pounds. But they also note that not everyone loses weight with the diet pill and most people will regain the weight if they don't make permanent changes to their diet and lifestyle.

There are few long-term studies that examine long-term use of Adipex, although as previously noted, it is not uncommon for the medication to be used for longer than 12 weeks.

Prescription vs. Online Availability

Because Adipex-P is one of the more popular drugs to lose weight, you'll find many online sources that claim to sell Adipex-P or drugs like Adipex-P. Keep in mind that you need a prescription to get this medication. Many of the companies that sell pills "like Adipex-P" without a prescription have not been verified by the FDA for safety or effectiveness. 

Because this drug can be habit-forming and because you may experience side effects while taking Adipex-P, you should visit your own doctor and review your full health history before you decide to use the medication. If you decide to try the diet medication buy it from a trusted pharmacy. Then communicate with your doctor about any side effects you experience and about whether or not the Adipex-P is helping you to lose weight.

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Article Sources
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