Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s) and published for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to prescription medication.
Adipex-P is a prescription drug approved by the Food and Drug Administration (FDA) in the U.S. for treating obesity. It’s one of the most commonly-prescribed weight loss medications on the market.
Adipex-P is the brand-name version of the drug, and the generic version is called phentermine. These two terms refer to the same active drug ingredient so we'll use them interchangeably throughout this article.
In this article we’ll review medical research on Adipex-P to provide our determination on whether the medication is safe and effective for weight loss. We'll overview side effects, explain whether the generic version is likely to be as effective, and share before-and-after images from a real user of the drug.
Does Adipex-P Work for Weight Loss?
Adipex-P has been extensively studied in clinical trials for its efficacy at causing weight loss.
One medical trial published in 2006 tested whether Adipex-P could cause weight loss in obese patients. The study authors found that after 14 weeks, nearly 90% of the Adipex-P patients lost 5% or more body weight, and 50% of Adipex-P patients lost 10% or more body weight. This is a significant amount of weight loss given the relatively short trial duration.
A meta-study published in the Obesity journal examined the long-term effectiveness of Adipex-P. The researchers tracked results from patients using the drug continuously for up to 24 months. The group taking Adipex-P for over 12 months lost 7.4% more weight than a control group that was taking placebo pills.
A medical review published in 2014 analyzed data from 6 individual trials on Adipex-P. The researchers found a statistically significant weight loss result in all trials. The average weight loss was 13.91 pounds, and the studies ranged from 2-24 weeks.
Based on the available medical data, we consider Adipex-P effective for treating obesity.
Adipex-P Side Effects
Adipex-P does have a risk of side effects which is outlined in both medical studies and on the drug's label.
A medical review found the following side effects to be the most common from Adipex-P use: anxiety, palpitations, headache and insomnia. These side effects are relatively minor for a pharmaceutical medication.
Adipex-P's FDA label shares a warning about using the medication in combination with other weight loss treatments, whether prescription drugs or over-the-counter (OTC) drugs, for more than "a few weeks." The safety of using Adipex-P in conjunction with other treatments has not been proven, and the drug manufacturer recommends against it.
This drug label is free of a "black box" warning, which is a warning of side effects can be life-threatening which is required by the FDA when appropriate. This means that Adipex-P may be safer than some other prescription medications which do have a black box warning.
Based on the previously-referenced drug label, Adipex-P is typically prescribed at a dosage of 37.5 milligrams (mg) and is taken once daily. Some patients are prescribed a half-dose, which equals 18.75 mg daily.
The benefit of a lower Adipex-P dose is that it may reduce the risk of side effects. The drug label even states the following: "dosage should be individualized to obtain an adequate response with the lowest effective dose."
Less weight loss can be expected from a lower dose, but so long as the weight loss is consistent, a doctor may keep their patient on the lower dose for safety reasons.
Should I Take the Generic Version?
Patients are often curious about whether they should take the generic or the branded version of a drug, given that both contain the same active ingredient(s).
As we suggested in our phentermine reviews article, the generic may be the better option.
A thorough meta-study published in the PLOS Medicine journal compared the effectiveness of generic and branded drugs. The study authors analyzed data from over 2 million patients and found generic and branded drugs to be equivalently effective.
Generic drugs can be cheaper than brand-name drugs, so we would recommend that patients speak to their doctor about phentermine rather than Adipex-P.
How Does Adipex-P Work?
Adipex-P is an appetite suppressant. When patients take Adipex diet pills, the level of a neurotransmitter called norepinephrine increases significantly in their brain.
A medical review documents a potential mechanism of action of Adipex-P: the drug appears to inhibit expression of a chemical compound in the brain called neuropeptide Y which sends hunger signals to the body. However, this needs to be confirmed with further research.
Adipex-P is chemically similar to amphetamine, and can cause similar effects to the body such as central nervous system stimulation and increased heart rate and blood pressure. The medical review linked above states that the medication causes a "continuous fight-or-flight response in the body." This is why it may cause anxiety in some patients.
Is Adipex-P Available Over-The-Counter (OTC)?
Adipex-P is not available OTC. The medication requires a prescription and cannot be legally purchased in a drugstore or online without one.
Typically, pharmaceutical drugs are not available OTC, and especially so for drugs in categories like weight loss that have the potential for abuse.
Adipex-P can be purchased online with a prescription. Amazon has a service called Amazon Pharmacy that allows patients to contact pharmacists virtually, but it's unclear to us whether a patient will still need to go to a local doctor for Amazon's service to work.
We recommend avoiding any merchant, online or otherwise, that sells Adipex-P without requiring a prescription. This may increase the risk of purchasing fraudulent medication which can be harmful.
OTC Weight Loss Options
There exist several over-the-counter (OTC) weight loss products that don't require a prescription, and have medical research backing. We are not suggesting that these products are as effective as Adipex-P; just that it may be worthwhile for an overweight patient to discuss these options with their doctor given their documented efficacy and lack of significant side effects.
We recommend dietary fiber as a safe and effective weight loss supplement.
An extensive medical review published in The Journal of Nutrition found that dietary fiber intake directly predicts weight loss when consumed at a high enough dose. Fiber is zero-calorie plant matter that makes you feel full faster, and consume fewer calories overall.
The fiber supplement we recommend is SuperGut Fiber Mix. It contains a clean and effective formulation: a blend of three different types of unflavored dietary fiber and zero additive ingredients. It can be mixed into liquids or foods. Interested consumers can buy SuperGut fiber at this link.
We recommend using two fiber mixes per day, which provides 16 g of total fiber. This is within the effective fiber dosing range associated with the greatest weight loss outcomes in the above-linked study (8-29 additional grams per day).
Medium-chain triglyceride (MCT) oil is another dietary supplement which has been shown in clinical trials to cause weight loss.
MCT oil is quickly absorbed by the body and increases metabolic rate, which causes fat loss. A meta-study on MCT oil documented weight loss of 1.12 pounds over 10 weeks. This equates to a potential annualized weight loss of 5.84 pounds with MCT oil supplementation.
We recommend Bulletproof MCT Oil as our top MCT oil product, because it has a clean and effective formulation. The only ingredient is MCT oil derived from coconuts, and the product has no questionable additives. Interested consumers can buy Bulletproof MCT Oil at this link.
The effective dose range of MCT oil for weight loss (based on the medical review) is 1.7 g to 10 g per day. Bulletproof's MCT oil provides 14 g in one tablespoon, so around two-thirds of one tablespoon should be a maximally-effective dosage.
Adipex-P User Reviews
Adipex-P has been reviewed over 400 times on Drugs.com, which is an online resource for patients to publish personal reviews of medication they've been prescribed.
The average rating for Adipex-P is 8.9/10, which is the highest average rating of any prescription drug that we've reviewed at the time of updating this article.
The top positive review is from a user named "SheilaD" who claims that the drug is effective for weight loss and had minimal side effects:
"Started Adipex 11 days ago, weighed myself today and have lost 11 pounds."
The top negative review is from a user named "SJ" who claims that the drug is ineffective and expensive:
"Teva changed adipex formula (no blue dots anymore) and although they say that was the only change, these are worthless. Not only did the cost go up, but they are ineffective. I spent $600 for 90 supply!!! I have to take 3 whole pills to get any effect whereas the pills with blue dots 1 to 1.5 was sufficient."
Adipex-P Before-and-After Images
Before-and-after images from real users are often popular for weight loss medications, since many patients are considering the drug for both health and aesthetic benefit.
One of the most popular YouTube reviews of Adipex-P comes from a channel called "Katie G." and the creator shares before-and-after images of their 70 pound weight loss caused by Adipex-P.
The video has achieved over 200,000 views at the time of updating this article:
Adipex-P and Alcohol
Drinking alcohol while taking Adipex-P may cause harmful interactions and is inadvisable. The drug's FDA label states that "concomitant alcohol use may result in an adverse drug reaction."
The label also includes "usage with alcohol" in a "Warnings and Precautions" section.
Given that even moderate alcohol use appears to cause health risks when combined with Adipex-P use, we would strongly suggest that patients are honest with their doctor about their alcohol intake and ability to quit before being prescribed this drug.
Patients unable to quit alcohol may benefit from speaking with their doctor about alternative weight loss medications that don't have this potential interaction.
Adipex-P Vs. Adderall
Patients are often comparing Adipex-P and Adderall for weight loss, because many individuals use Adderall recreationally and have noted weight loss as a side effect.
Adderall is an amphetamine, which means it's a stimulant that increase calories burned at rest and can cause weight loss.
Adderall is not approved by the FDA for weight loss, so using it for this health outcome would be an "off-label" use, and we always recommend avoiding off-label uses of prescription medication.
We would recommend that patients interested in a pharmaceutical approach to weight loss speak with their doctor about Adipex-P instead of Adderall.