Adipex is the most popular brand of phentermine in the United States ( 1 ). This prescription-only medication supports weight loss by suppressing appetite and increasing energy. In combination with healthy diet and exercise, it can help you transform your lifestyle and reach your weight loss goals faster.


What is Adipex?

Before you consider taking Adipex weight loss pills, it’s important to know what they contain, what they look like and how they work.


Adipex-P structure

The active ingredient in Adipex diet pills is phentermine hydrochloride (phentermine HCL). Each pill contains 37.5mg of phentermine HCl, which is equivalent to 30mg phentermine base.

This prescription appetite suppressant is available in tablet and capsule form, and has different inactive ingredients dependent on preparation.

The inactive ingredients in Adipex tablets include: corn starch, lactose (anhydrous), magnesium stearate, microcrystalline cellulose, pregelatinized starch, sucrose and FD&C Blue #1. The capsules’ inactive ingredients are: corn starch, gelatin, lactose monohydrate, magnesium stearate, titanium dioxide, black iron oxide, FD&C Blue #1, FD&C Red #40 and D&C Red #33 ( 2 ).


adipex-p tabletAdipex tablets are blue and white with an oblong shape. Each tablet is scored and embossed with “ADIPEX-P” and “9-9”. Each bottle contains 30 tablets.

Adipex capsules are opaque capsules that are half bright blue and half white, with two dark blue stripes around the white end. Each capsule is imprinted with “ADIPEX-P” and “37.5”. The capsules are packaged in bottles of 100 ( 2 ).

Mechanism of Action

Phentermine hydrochloride is a sympathomimetic amine that stimulates the nervous system to promote weight loss ( 3 ).

It promotes the release of norepinephrine: a neurotransmitter that triggers “fight or flight” to increase energy and reduce hunger. It also stimulates the release of adrenaline (epinephrine) to other areas of the body, which leads to the breakdown of stored fat ( 2 ).

Similar to other weight loss medications, Adipex works best when combined with a healthy diet and regular exercise.

Interested in buying Adipex? Learn more here: Where to Buy Adipex.

No prescription? Consider Phen Caps, a popular weight loss supplement available online at

Who Takes Adipex?

overweight man holding glass of water in one had and Adipex capsules in the other
Adipex is designed for overweight and obese patients who have struggled to lose weight on their own

This medication is designed as a short-term treatment for exogenous obesity ( 2 ). This type of obesity can occur from eating too much, moving too little, or a combination of the two ( 4 ). Phentermine is not designed to treat obesity caused by other medical problems.

Adipex is an option for patients with a body mass index (BMI):

  • Greater than 30 kg/m2, or
  • Greater than 27 kg/m2 if weight-related conditions (e.g. type 2 diabetes or high cholesterol) are also present

Still, phentermine is not appropriate or safe for everyone – even within these BMI ranges ( 2 ).

Adipex Dosage

The standard dose of Adipex is 37.5 mg once per day.

Alternatively, some users split their tablets in half. These patients may take just one half of the pill (18.75 mg) each day, or split the tablet to take the two half doses at different points during the day ( 2 ). The second option is a common strategy for people who struggle with afternoon or nighttime cravings.

Phentermine is designed as a short-term treatment for obesity, so it should not be taken for more than 12 weeks at a time ( 2 ). If your doctor believes that you could benefit from a longer treatment period, he or she can weigh the pros and cons of prescribing Adipex (phentermine) off-label for longer.


Overdosing on phentermine is dangerous. Taking more medication than prescribed does not increase effectiveness and can have serious, potentially-fatal, consequences ( 5 ).

Call emergency medical services or go to a hospital right away if you suspect that you or a loved one may have overdosed on phentermine.

Learn more here: Phentermine Overdose

Adipex Side Effects

Adipex is highly effective for weight loss, but it can also cause many side effects – ranging from relatively mild to undeniably severe. While some people experience intense reactions, others have no side effects at all.

Common Side Effects

The three most common Adipex-P side effects are:

  • Dry mouth (xerostomia)
  • Trouble sleeping (insomnia)
  • Constipation

Side effects are typically most severe at the start of treatment, as the body works to adjust to phentermine.

Here are the percentages of current users who have experienced phentermine’s most common side effects, as self-reported in a recent online poll ( 6 ):

Poll Results (graph): Top 10 Phentermine Side Effects
Results of a 2019 poll on users' most common phentermine side effects

Severe Side Effects

Although less common than the reactions listed above, severe side effects of Adipex are dangerous and potentially life-threatening.

Symptoms of a severe reaction to phentermine include ( 2 ):

  • Fainting
  • Swelling of feet or ankles
  • Trouble breathing
  • Extreme weakness/inability to carry-out daily activities
  • Chest or lung pains

If you or someone you know experiences any of these reactions while taking Adipex, call 911 or get to a hospital right away.

Symptoms of an Adipex Allergy

Like with any drug, it is possible to have an allergic reaction to Adipex-P.

Signs of an Adipex allergy include ( 7 ):

  • Severe dizziness
  • Trouble breathing
  • Itching
  • Swelling
  • Rash
  • Chest pain

Seek immediate medical attention if you or someone you know experiences any of these symptoms while taking Adipex.

How to Take Adipex

young, female doctor smiling from behind a desk
Take Adipex diet pills exactly as prescribed

​Adipex 37.5 mg should be taken once daily on an empty stomach: either 30 minutes before breakfast or 1-2 hours after eating ( 5 ).

Do not take this medication late at night or just before bed because it can cause insomnia.

If you have an atypical sleep-wake schedule (such as shift work) that makes early-morning dosing disadvantageous, discuss an individualized phentermine schedule with your doctor at the initial appointment.

NEVER adjust dosage or schedule without consulting your doctor and pharmacist first.

Adipex Diet

The best Adipex diet is a balanced eating plan that you can maintain over the long term.

While it may be tempting to jump into the latest fad diet or slash calories dramatically to lose weight quickly, avoid extreme diets unless they are specifically recommended & supervised by your doctor. Instead, take advantage of the medication’s appetite-suppressing power to incorporate more healthy eating habits – like portion control and getting your “five a day” of fruits and vegetables – into your daily routine.

There is no specific or perfect “Adipex diet”, but consistently eating healthy portions nutritious meals will help you lose weight and keep it off ( 8 ).

Adipex Results

slim woman measuring her waist
Browsing through Adipex before and after stories helps inspire you to reach your own weight loss goals!

These pills suppress appetite, curb cravings and increase energy to help patients lose weight quicker and easier ( 3 , 9 , 10 ). Average weight loss with Adipex, and phentermine in general, is about 1-4 pounds per week.

Here are two inspiring Adipex weight loss stories from real women:


Kristin before and afterStarting Weight: 204 lb | Current Weight: 149 lb | POUNDS LOST: 55

Kristin embarked on her weight loss journey to get healthy for herself and her daughter. After losing over 50 pounds, she loves shopping for smaller clothes.


Neva before and afterStarting Weight: 230 lb | Current Weight: 184 lb | POUNDS LOST: 46

Neva asked her doctor about Adipex after being diagnosed with high blood pressure, and – soon after – type 2 diabetes. She hated having to throw away all of her expensive clothes as she lost weight, but now she loves being to slip into the same size dress she wore at her wedding!

Adipex Reviews

Over the past fifteen years, hundreds of phentermine users have submitted their Adipex reviews, successes and struggles. Patients praise this brand for its high effectiveness, but complain that it’s only available in one dose and typically more expensive than generic phentermine.

Adipex has an average user rating of 4.1/5:

(40 votes)

Here are some recent Adipex reviews from real users:

Caro - No appetite
Read More
I've lost 25 kilos with Acxion. I took a daily dose for 4 months and then rested for a month, and then for the last 4 months I've been taking it every other day or once every three days.
Reyna - Super Effective
Read More
Hello! I have been taking Acxion AP (30mg) and honestly it has worked very well for me. I’ve been taking it for about a year & it still hasn’t lost its effectiveness, now I only use it to maintain my ideal weight.
Greta - 6 Kilos
Read More
I take acxion tabs, chromium and metformin to lose weight. Since starting I got sick and took a ton of medications and it was hard to keep on track but I lost 6 kilos in 1 month. The headaches are better now so I'll keep taking it.

Where to Buy Adipex

Phentermine is a controlled substance, so the only way to buy Adipex legally is by filling a doctor’s prescription at a DEA-registered pharmacy.

It is illegal to buy Adipex without a prescription.

Is Adipex a controlled substance?

Yes, phentermine is class IV controlled substance in the US and abroad ( 2 ). Sale and distribution of Adipex is closely monitored and controlled.

Will Adipex show up on a drug test?

Yes. Due to its chemical similarity to amphetamines, phentermine can produce a false-positive for amphetamines (meth) on a standard drug test ( 11 ). However, phentermine is NOT an amphetamine.

Expect phentermine to appear on a urine drug screen for 4-7 days after your last dose of Adipex ( 11 , 12 ). You may test positive for longer if you have been taking phentermine for a long time or at higher-than-normal doses.

Interested in buying Adipex? Learn more here: Where to Buy Adipex.

No prescription? Consider Phen Caps, a popular weight loss supplement available online at

Adipex Alternatives

Adipex-P is the most well-known brand of phentermine in the US, but that doesn’t mean it is the only option.

Adipex vs Phentermine

One of the most common questions people ask is, “Is Adipex phentermine?” The answer is yes – Adipex is a popular brand of phentermine diet pills. If you’re comparing phentermine to Adipex, you are comparing a brand name pill to the generic form of the same medication. Generic phentermine is typically cheaper and available in a wider variety of doses.

Contrave vs Adipex

Contrave contains a combination of naltrexone and bupropion extended-release to suppress appetite and control cravings ( 13 , 14 ). It can be taken for longer than Adipex-P and it is not a controlled substance, but the weight loss pills can cause a variety of serious side effects.

Bontril vs Adipex

Bontril is a popular brand of phendimetrazine, another drug that promotes weight loss.

Both medications act as central nervous system stimulants, and are both controlled substances ( 15 ). However, patients respond to these two drugs very differently and some individuals experience better outcomes with Bontril.

Didrex vs Adipex

Didrex is the brand name for the benzphetamine: another prescription appetite suppressant. Similar to Adipex and Bontril, Didrex decreases the appetite and boosts energy by enhancing the activity of the central nervous system ( 16 ).

Didrex is a higher, class III controlled substance, but Adipex is more potent.

Over the Counter Options recommends Phen Caps if you can’t (or don’t want to) take Adipex.

Phen Caps is a powerful dietary supplement that contains nine all-natural ingredients that suppress the appetite and boost energy, without the side effects. They do not contain any phentermine HCl, which means that Phen Caps are legally available online and without a prescription.

Who Makes Adipex?

Adipex diet pills are manufactured by Teva Pharmaceuticals USA, Inc. They have been producing and marketing this diet pill since 1990.

The contact information for Teva Pharmaceuticals USA is ( 17 ):

Teva North America – US Headquarters
1090 Horsham Road
North Wales, PA 19454 USA

1-888-TEVA-USA (1-888-838-2872)

TEVA Pharmaceuticals logo

  1. CVS. (2019, April). Phentermine Hydrochloride.
  2. U.S. Food and Drug Administration. (2012). Adipex-P (phentermine hydrochloride) capsules label [Brochure].
  3. National Center for Biotechnology Information. PubChem Compound Database: CID=4771 (Phentermine).
  4. Journal of Obesity & Weight Loss Therapy Open Access. (n.d.). Exogenous Obesity.
  5. Mayo Foundation for Medical Education and Research [MFMER]. (2018). Drugs and supplements: Phentermine (Oral Route).
  6. Members of “Losing Weight with Phentermine” Support Group on Facebook & Forum. (2019, March 13). [User Report of Common Phentermine Side Effects]. Unpublished raw data.
  7. (2018, September 25). Phentermine: Drug Uses, Dosage & Side Effects.
  8. Wing, R. R., & Phelan, S. (2005). Long-term weight loss maintenance. The American Journal of Clinical Nutrition, 82(1), 222S-225S.
  9. Rueda-Clausen CF, Padwal RS, Sharma AM. New pharmacological approaches for obesity management. Nat Rev Endocrinol. 2013;9(8):467-478.
  10. Weintraub M, Hasday JD, Mushlin AI, Lockwood DH. A double-blind clinical trial in weight control. Use of fenfluramine and phentermine alone and in combination. Arch Intern Med. 1984;144(6):1143-1148.
  11. Marin SJ, Doyle K, et al. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry. J Anal Toxicol. 2016;40(1):37-42.
  12. National Library of Medicine (US). (2006, May 2). PHENTERMINE.
  13. Tek C. Naltrexone HCI/bupropion HCI for chronic weight management in obese adults: patient selection and perspectives. Patient Prefer Adherence. 2016;10:751-759.
  14. Sherman MM, Ungureanu S, Rey JA. Naltrexone/Bupropion ER (Contrave): Newly approved treatment option for chronic weight management in obese adults. P T. 2016;41(3):164-172.
  15. National Center for Biotechnology Information. PubChem Compound Database: CID=12460 (Phendimetrazine).
  16. National Center for Biotechnology Information. PubChem Compound Database: CID=11558159 (Benzphetamine HCl).
  17. Teva Pharmaceuticals USA, Inc. (2019). Teva USA.
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