What is Adipex?

Adipex is the most popular brand of phentermine weight loss pills in the United States ( 1 ). It is a prescription-only stimulant that supports weight loss by suppressing appetite, boosting energy, and accelerating fat burn ( 2 ).


Too busy for the full read? Here’s what you need to know:

  • Adipex is prescribed for short-term weight loss to overweight and obese patients in the US.
  • The medication stimulates the nervous system, increasing energy levels and reducing feelings of hunger.
  • Adipex is available as tablets or capsules.
  • It should be taken for no longer than 12 weeks.
  • In studies, users lost 10% of their initial weight.
  • Side effects can range from mild to severe. Allergic reactions can also appear.
  • Since it is a prescription-only drug, you should not buy Adipex online.
  • The medication should be combined with a healthy diet and exercise for the best results.

What is Adipex used for?

Adipex pills can assist those who are overweight or obese with short-term weight loss.

A body mass index (BMI) calculation is required to confirm whether an individual is overweight, and Adipex should only be prescribed to patients with:

  • BMI ≥ 30 kg/m2, or
  • BMI ≥ 27kg/m2 with one or more weight-related complications.

Eligible weight-related complications include:

  • High blood pressure (hypertension) that is well controlled with medication
  • Type 2 diabetes
  • High cholesterol (hyperlipidemia) ( 4 ).

Adipex is a Schedule IV controlled substance, and you must, therefore, only take it if it has been prescribed for you by a doctor ( 5 ).

How Does Adipex Work?

Adipex mechanism

Phentermine HCL is the active ingredient in Adipex that is responsible for aiding weight loss. The other Adipex ingredients are inactive, meaning they don’t affect the body, but may still be required as preservatives or coatings ( 5 ).

Phentermine is a sympathomimetic amine that works by stimulating the nervous system. This leads to the release of norepinephrine, which increases energy levels and reduces feelings of hunger. Adrenaline release is also stimulated, leading to the breakdown of fat stored within the body ( 6 ).

Like other weight loss medications, Adipex will be most effective when combined with a healthy diet and physical activity.

Adipex is not an amphetamine, but the chemical structures of amphetamine and phentermine have some similarities.

Adipex will not suit everyone, and there are specific contraindications to taking this medication. Therefore, your doctor should thoroughly review your medical history and current medications to ensure they suit you. It is essential, to be honest with your prescribing doctor when considering Adipex.

How Long Does It Take for Adipex to Work?

Adipex is a short-term treatment that should be taken for no longer than 12 weeks. Weight loss should be seen within the first few weeks of treatment, but if this does not occur, Adipex should be discontinued ( 5 ).

How Long Does Adipex Last?

After taking Adipex, it becomes effective in approximately 2 hours. Its effects last for around 8 hours ( 7 ).

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When and How to Take Adipex

Unless your doctor has advised you otherwise, the best time to take Adipex is first thing in the morning. It can be taken with or without food ( 5 ).

However, as the effects of phentermine last for around 8 hours, individuals who struggle with afternoon or evening cravings may find that the effect of phentermine wears off too quickly. If this occurs, it is possible to split Adipex 37.5mg tablets in half so that one half is taken in the morning and the other early afternoon. Taking the medication on such a schedule helps to sustain the therapeutic impact of phentermine over a more extended period.

An Adipex capsule cannot be split in the same manner, so if you are considering Adipex capsules vs tablets this may be relevant to your decision-making.

The maximum dosage is 37.5mg daily, which should not be exceeded. Taking more than this dose will not increase weight loss but will significantly increase the risk of side effects and even a phentermine overdose which could be fatal ( 8 ).

What Does Adipex Look Like?

Adipex tablets are blue and white with an oblong shape. Each tablet is scored and embossed with “ADIPEX-P” and “9-9”.

Adipex Tablets

The score line makes it easier to split the tablet in half. Each bottle contains 30 tablets, equivalent to a one-month supply.

Adipex capsules are opaque capsules. One half is bright blue, and the other is white, with two dark blue stripes around the white end.

Adipex pills

Each capsule is imprinted with “ADIPEX-P” and “37.5”. The capsules are packaged in bottles of 100 ( 5 ).

What Does Generic Adipex Look Like?

Adipex 37.5 mg is available on prescription as generic phentermine. There are many manufacturers of phentermine, and different strength tablets and capsules are available.

These all differ in appearance depending on the manufacturer, strength, and preparation.

Related: How to Spot Fake Phentermine

Side Effects of Adipex

Adipex side effects

Adipex 37.5 mg is an effective weight loss medication. However, some people may experience side effects when taking Adipex. The side effects can range from mild to severe.

Some people may experience several side effects, whereas others may take the medication for months and not experience any adverse effects. You should speak to your doctor if you are concerned about a potential side effect or think Adipex may not suit you.

Common Side Effects

The most commonly reported side effects of Adipex occur as a result of central nervous system stimulation.

Common side effects of Adipex include:

Other common reactions when taking Adipex include:

If you notice a side effect that persists, worsens, or interferes with your daily life, you must seek medical advice immediately ( 9 ).

Serious Side Effects

Phentermine weight loss pills such as Adipex have been associated with serious and potentially fatal heart and lung problems.

If you experience any of the following symptoms while taking Adipex, you must call 911, go to the hospital or speak to a doctor immediately:

  • Chest pain
  • Difficulty breathing
  • Fainting
  • Adipex is available as tablets or capsules.
  • Severe headache
  • Seizure (fitting)
  • Blurred vision
  • Swelling of the legs, ankles, or feet
  • Slurred speech
  • Weakness affecting one side of the body
  • Reduced ability to exercise.

One of the milder Adipex side effects is mood swings. Still, Adipex can also be associated with dramatic emotional changes or alterations in mood. This includes extreme happiness or sadness. If this occurs, you should stop taking Adipex and speak to a doctor immediately, as the medication may not suit you.

Allergic Reactions

Rarely, an allergic reaction to phentermine may occur.

Symptoms include:

  • Rashes or hives
  • Itching or swelling, especially of the face, mouth, tongue, or throat
  • Severe dizziness
  • Difficulty breathing, including feeling wheezy or having a tight chest.

If any of these symptoms of an allergic reaction occur, you must stop taking Adipex and call 911 or seek immediate medical attention.

What Are the Long-Term Effects of Adipex?

Most people who experience side effects when taking Adipex or another phentermine-containing medication will only have symptoms while they are taking the medication.

Adipex 37.5 mg should only be taken for up to 12 weeks at a time. It is unusual to experience long-term side effects after finishing a course. However, some users report ongoing hair loss after completing a course of Adipex ( 9 ).

Adipex Withdrawal

There is a strong potential for addiction with all phentermine-containing products, which is one of the reasons that you must not exceed the 12-week course.

The addictive nature of phentermine means that some people experience withdrawal when stopping Adipex, even if they have only taken a short course.

Withdrawal symptoms include feeling low and other mood changes, insomnia, fatigue, diarrhea, or trembling. These withdrawal signs are likely to be most intense during the four days after stopping Adipex. Still, low mood and tiredness could persist for weeks ( 10 ).

Your doctor may advise you to slowly reduce your dose of Adipex at the end of your treatment course, as this may help to avoid withdrawal symptoms.

Recommended: PhenQ has no side effects and is available without a prescription.

Who Can’t Take Adipex?

Adipex Contraindications

As with all medications, you must be aware of the contraindications, precautions, and interactions associated with Adipex and phentermine.


Individuals should not take Adipex with the following conditions:

  • Primary pulmonary hypertension
  • Heart valve disease
  • Heart or blood vessel disease, including coronary artery disease, stroke, arrhythmias (abnormal heart rhythms), congestive heart failure, or hypertension that is not well controlled on medication
  • Thyroid disease
  • Glaucoma
  • A previous or current drug addiction or dependency disorder
  • An allergy to diet pills or another medication.

Adipex may not be suitable for those with kidney disease or impairment but may be prescribed depending on a patient’s kidney function.

Adipex is unsuitable for those already taking a different weight loss pill ( 5 ).


It is not safe to take Adipex while pregnant. Adipex must not be taken during pregnancy or when trying to conceive.

We are often asked when it is safe to breastfeed after Adipex, but nursing mothers are usually advised not to take this diet pill. This is because phentermine can remain in your system for up to 7 days, creating a risk of phentermine crossing into the milk, which could be harmful to a baby ( 5 ), 11 ).

Some patients with diabetes may be advised by their doctor to reduce the dose of their diabetes medications, including insulin, to avoid low blood sugar ( 5 ).

Adipex is only suitable for patients aged 18 or older.


There are some people for whom Adipex is not recommended due to a risk of interactions with other substances. Drug interactions may occur with monoamine oxidase inhibitors (MAOIs) and adrenergic neuron-blocking drugs ( 5 ).

Taking Adipex and alcohol together can increase the risk of side effects affecting the heart and nervous system. It is, therefore, advisable to abstain from drinking alcohol while taking Adipex. Adipex is not suitable for individuals with alcohol dependence.

Wellbutrin is an antidepressant that can also help with nicotine addiction. The generic preparation is bupropion. Wellbutrin and Adipex must not be taken together, as these two medications can interact with the potential to cause seizures ( 12 ).

There is also a risk of major side effects between Lexapro and Adipex. Lexapro is also sold as the generic antidepressant escitalopram. When combined, there is a risk of serotonin syndrome. This rare but serious condition can lead to a coma and even death ( 13 ).

How Much Weight Can I Lose on Adipex?

Adipex Weigth Loss Results

In clinical trials lasting up to 12 weeks, taking phentermine alongside dieting and exercising led to significantly greater weight loss than taking a placebo pill.

In one study, the average weight loss was around 4kg.

In another study, over 80% of those taking phentermine lost 5% or more of their initial weight, and over half of the individuals lost 10% or more.

Therefore, average weight loss on Adipex is greater than with diet or exercise alone ( 14 ), 15 ).

How Much Weight Should You Lose on Adipex?

It is natural to want to lose as much weight as possible when taking Adipex. But slow and steady weight loss is preferable to rapid losses, which are often unsustainable.

The average weekly weight loss when taking phentermine is around 1 pound. Your one-month Adipex results could show about 3 to 5 pounds weight loss ( 16 ).

The key is to use the time when taking Adipex 37.5 mg to adopt healthy lifestyle changes, such as eating healthily and doing more physical activity. Then, when your course of Adipex ends, you will have developed a healthier lifestyle.

User Reviews

Based on recent user reviews and Adipex success stories, Adipex has an average user rating of 4.3 out of 5.

Adipex is a popular choice for weight loss assistance. Most users claim that Adipex has helped them reach their weight loss goals ( 17 ).

Patients have said the following about Adipex:

Solange – Lost 55 pounds

“I didn’t starve myself and I was able to lose weight really fast. I exercised, ate right. I’ll keep working hard!”

Minnie – So super easy to take

“Not one side effect… and after three months I do not regret it at all. I’ve lost 26lbs so far”.

Rocco – The best

“Lost 15 pounds in my first month….What a great pill”.

Related: Read More Reviews About Adipex Here

Where Can I Buy Adipex?

Adipex use is tightly regulated because phentermine is a controlled substance. You will need to get a prescription before you can buy Adipex ( 18 ).

Suppose you have a prescription from your usual doctor or weight loss clinic and are wondering where to buy Adipex. In that case, you can visit a nearby pharmacy or use your prescription to order Adipex online.

We are often asked if it is possible to get an Adipex prescription online. Sometimes, pharmacies offer a prescription service after an online consultation with a doctor or pharmacist. This means you can buy Adipex online. However, using an online doctor may be unsafe, as it is impossible to complete a physical examination, and follow-up is not offered. Therefore, you may put your health at risk by requesting Adipex in this way.

Related: Learn How to Get a Prescription for Phentermine

Recommended: Buy PhenQ, available without a prescription, to lose weight fast.

How Much Does Adipex Cost?

The cost of weight loss drugs, including Adipex, can vary significantly. The following table provides the estimated prices for Adipex tablets and capsules.

PharmacyCost for a 30-day supply of 37.5mg tabletsCost for a 30-day supply of 37.5mg capsules

*prices updated 1st July 2022 ( 19 ).

Buying Adipex at a lower price may be possible if you have insurance, a prescription saving card, or a valid Adipex coupon.

How Does Adipex Compare to Other Weight Loss Drugs?

Compare Adipex

If you hope to lose weight, you may feel overwhelmed by the choice of available diet pills. Our comparison tables may help you decide if Adipex is right for you.

Adipex vs Phentermine

Phentermine is the generic version of Adipex and is cheaper.

Medication FormsCapsules TabletsCapsules Tablets
Available Doses37.5mg8mg 15mg 18.75mg 30mg 37.5mg
CostApproximately $70 per monthLess than $10 per month (19)

Bontril vs Adipex

Like Adipex, Bontril is a central nervous system stimulant, but its active ingredient is phendimetrazine, not phentermine.

Medication FormsCapsules TabletsCapsules Tablets
Dosing ScheduleTaken once dailyTaken three times daily
CostApproximately $70 per month$7 to $24 per month for generic phendimetrazine pills (19)

Related: A Detailed Review of Bontril

Contrave vs Adipex

Contrave contains naltrexone and bupropion to reduce the appetite and make you feel fuller sooner. Contrave can be used longer if initial weight loss is achieved.

Medication FormsCapsules Tablets Tablets
Dosing ScheduleTaken once dailyUp to 2 tablets twice daily
Duration12 weeks maximumCan be taken for a year or more

Related: A Detailed Comparison of Contrave and Phentermine

Adipex vs Adderall

Adderall is a central nervous system stimulant that contains amphetamine and dextroamphetamine. It is used to treat ADHD and can cause weight loss, but the FDA does not license it for treating obesity in the USA ( 20 ).

Approved for treating obesity by the FDA?YesNo
Risk of addiction?Yes, therefore for short-term use onlyYes

Didrex vs Adipex

Didrex contains benzphetamine and is only for short-term use. It affects chemicals in the brain to suppress the appetite and boost energy use.

Dosing ScheduleTaken once dailyOne to three times daily, depending on appetite
CostApproximately $70 per month$27 to $138 for one month’s supply if taken three times daily (19)

Related: A Detailed Comparison of Didrex and Phentermine

Tenuate vs Adipex

Tenuate contains diethylpropion which suppresses feelings of hunger.

Dosing ScheduleTaken once dailyThree times daily before meals
PrecautionsMay rarely cause significant mood alterationsCan worsen anxiety and other mental health conditions

Related: A Detailed Comparison of Tenuate and Phentermine

Qysmia vs Adipex

Although Adipex contains phentermine, Qysmia contains phentermine and topiramate to reduce the appetite and make you feel fuller more quickly.

Dosing ScheduleTaken once daily for 12 weeksGradual increasing schedule then use for a year or more
CostApproximately $70 per month$177 to $218 per month when taken at the highest dose (19)

Who Makes Adipex?

Adipex is manufactured by Teva Pharmaceuticals USA, Inc, headquartered in North Wales, Pennsylvania ( 21 ).

Teva Pharmaceuticals Logo

Frequently Asked Questions

What’s the difference between Adipex and Adipex-P?

There is no difference between the two. The names Adipex and Adipex-P are sometimes used interchangeably.

Is Adipex a controlled substance?

Adipex is a Schedule IV controlled substance ( 5 ).

Is Adipex FDA Approved?

The FDA approves Adipex for short-term use (up to 12 weeks).

What are the ingredients in Adipex-P?

Adipex capsules and tablets are made with active and inactive ingredients. The active ingredient is Phentermine HCL. The inactive ingredients in Adipex differ for capsules and tablets and can be found in the following table ( 23 ).

Adipex CapsulesAdipex Tablets
Active IngredientsPhentermine HCLPhentermine HCL
Inactive IngredientsBlack iron oxide, corn starch, D&C Red #33, FD&C Blue #1, gelatin, lactose monohydrate, magnesium stearate, propylene glycol, shellac, and titanium dioxide.Corn starch, lactose (anhydrous), magnesium stearate, microcrystalline cellulose, pregelatinized corn starch, and sucrose.

What is generic Adipex?

Adipex 37.5 mg is available as the generic pill phentermine.

What should I eat while taking Adipex?

For best results, you should follow a low-calorie, low-fat diet. Combining Adipex with a healthy diet makes it easier to continue this diet when the course finishes.

Does Adipex give you energy?

The phentermine in Adipex has a stimulant effect which may make it feel like you have been given a boost of energy. This can make it easier to increase physical activity.

Is Adipex safe?

The FDA has approved Adipex as safe for short-term use only.

Is Adipex a narcotic?

No, Adipex belongs to a group of drugs called stimulants.

Is Adipex addictive?

Adipex may cause addiction when taken long-term. However, addiction is much less likely when Adipex is taken for no longer than 12 weeks.

Does Adipex burn fat?

The stimulant properties of Adipex may increase the rate of fat burning to aid weight loss.

Does Adipex show up on a drug test?

Yes, Adipex might show up on a drug test.

Although phentermine in Adipex is not the same as amphetamine, its similar chemical structure may cause it to show up as amphetamine on a drug screen. Therefore, you should provide your prescription if asked to undertake a drug test ( 11 ).

How long does Adipex stay in your system?

Phentermine may still be detectable 4 to 7 days after taking your last dose of Adipex. This period may be longer if you have taken phentermine for a long time or if you have taken a higher dose than prescribed ( 11 ).

How do I take Adipex for the best results?

For best results, take Adipex as your doctor prescribes, alongside a low-calorie diet and regular physical activity. Only take Adipex for a maximum of 12 weeks.

How can I get Adipex over the counter?

Adipex can only be obtained with a prescription as it is a controlled medication.

How does Adipex make you feel?

If Adipex works well, it should make you feel less hungry and more energetic. However, as with all medications, there is a risk that you may experience unwanted side effects.

Why am I not losing weight fast on Adipex?

Adipex 37.5 mg should support steady weight loss of around 3 to 5 pounds per month. The best results are achieved by following a low-calorie diet and exercising regularly. If you do not lose weight despite lifestyle changes, Adipex may not suit you.

How can I lose weight quickly on Adipex?

To support long-term weight loss, you should make healthy lifestyle changes that you can sustain once the course of Adipex finishes. This will promote slow, steady weight loss on Adipex. In addition, you must not take more than the prescribed dose, as this will not increase weight loss but may increase the risk of adverse events.

How long can you take Adipex for?

Adipex should only be taken for 12 weeks at a time.

How much caffeine is in Adipex?

There is no caffeine in phentermine or Adipex.

However, it is wise to avoid other sources of caffeine, such as tea and coffee, as caffeine may also act as a stimulant. Combining caffeine and phentermine may therefore increase the risks of side effects.

What is the difference between Adipex and Abidexin?

Adipex is a controlled drug that contains phentermine, whereas Abidexin contains natural substances that may aid weight loss.

What is the best alternative to Adipex?

As an over-the-counter alternative to Adipex, we recommend PhenQ.

PhenQ is legally available online without a prescription. It does not contain phentermine. Instead, it suppresses the appetite and boosts energy with nine natural ingredients. PhenQ does not have the side effects associated with phentermine ( 22 ).


1. (Brands).                                     
2. (Phentermine Action).
3. Rueda-Clausen CF, Padwal RS, Sharma AM. New pharmacological approaches for obesity management. Nat Rev Endocrinol. 2013 Aug;9(8):467-78. doi: 10.1038/nrendo.2013.113. Epub 2013 Jun 11. PMID: 23752772.
4. (2022) Adipex Indications.
5. (2023) Adipex-P Label).
6. (2012) Phentermine and Topiramate.
7. (2023) Phentermine Absorption.
8. (2023) Overdose.
9. (2023) Side Effects.
10. (2023) Withdrawal.
11. (2023) Will Phentermine Show Up On A Drug Test?
12. (2023) Drug Interactions between phentermine and Wellbutrin XL.
13. (2023) Drug Interaction Report Lexapro – Phentermine.
14. Kim, K. K., Cho, J., Kang, C., Youn, B., & Lee, R. Effects on weight reduction and safety of short-term phentermine administration in Korean obese people. Yonsei Medical Journal. 2006; 47: 614-625. .
15. Kim, H. O., Lee, J. A., Suh, H. W., Kim, Y. S., Kim, B. S., Ahn, E. S., Roh, Y. J., Jung, S. G., Kim, J. M., Kang, M. K., Ahn, I. S., & Park, Y. G. Postmarketing surveillance study of the efficacy and safety of phentermine in patients with obesity. Korean Journal of Family Medicine. 2013; 34(5): 298-306.
16. (2023) Average Weight Loss.
17. (2023) Reviews.
18. (2023) How to Get a Prescription for Phentermine.
19. (Adipex-P Prices).
20. John P. Cunha, DO, FACOEP (2023) Belviq vs. Adderall.
21. Teva USA (Adipex Manufacturing).
22. (2023)
23. (Capsule label)