Gold Member Badge


  • You're all caught up!

What is the Difference Between Fastin & Phentermine?

author image Melissa Lind
Melissa Lind holds a Bachelor of Science degree from the University of Texas College of Pharmacy. She has over 20 years experience as a health-care professional, including pharmacy practice as a registered pharmacist, and experience in clinical research management and community college instruction in pharmacology and health topics. Lind has been a freelance writer and independent content provider since 2006.
What is the Difference Between Fastin & Phentermine?
Fastin dietary supplements no longer contain phentermine and are not prescription weight loss products. Photo Credit: mychadre77/iStock/Getty Images

Phentermine is a well-known prescription appetite suppressant that is approved for short-term use in the treatment of obesity and has been sold for many years under a number of brand names, including Fastin. The prescription form of Fastin containing phentermine was removed from the market in 1998. A new group of over-the-counter supplements sold under the brand name of Fastin are now available, but are very different from the former product. Some of these products contain a number of active ingredients that may be difficult to identify and may cause adverse reactions or drug interactions. Talk to your doctor about all of your health conditions and medications you are taking before getting any new prescriptions or taking any over-the-counter supplement.

Video of the Day


Phentermine was first approved as a prescription appetite suppressant in 1959 by the Food and Drug Administration. It is a controlled substance and is considered to be mildly addictive and may be abused, as it has effects that may be similar to amphetamine. It has been sold under many brand names. Ionamin, Adipex and Fastin were the most well known, but as it is an older drug; most people take the generic form. Though it is an effective appetite suppressant, phentermine may have side effects such as nausea, insomnia, increased heart rate and nervousness.

Discontinued Prescription Fastin

In the early 1990s, many physicians were prescribing phentermine with another weight-loss drug, fenfluramine, in a combination known as phen-fen. After a number of serious adverse events involving the practice, the drug fenfluramine was withdrawn from the market. Several of the brand name manufacturers discontinued making brand name phentermine, including the manufacturer of the brand name Fastin, which was discontinued by the manufacturer in 1998. Ionamin, Adipex-P and generic phentermine are still available. Currently available Fastin products do not have the prescription ingredient phentermine; they are dietary supplements.

Fastin Dietary Supplements

According to the manufacturer of Fastin over-the-counter products, the company purchased the Fastin name and trademark from the former prescription manufacturer and began producing a line of dietary supplements. The company currently lists three products with the Fastin brand name on its website, though others appearing in different formats can be found on the Internet -- none of which are similar to the old prescription Fastin with phentermine. The Fastin dietary supplement products carry names such as Fastin Multi-vite for Her, Fastin XR and Fastin Dietary Supplement and these products claim to help supress appetite. The products list ingredients such as dimethylamylamine, methylxanthine alkaloids and phenylethamine alkaloids, which may have side effects, including increased heart rate, nervousness and increased blood pressure, for some people.

Dietary Supplements

Prescription and over-the-counter products sold as medications must undergo rigorous clinical testing proving both safety and efficacy in animals and humans. They are also subject to manufacturing and testing standards of purity. Unlike medications, dietary supplements are considered food products by the Food and Drug Administration. They do not have to undergo the same clinical standards. Unless a dietary supplement has been shown to cause harm, it can be sold with few restrictions. Tell your doctor about medicines that you are taking and seek advice before starting a new dietary supplement

LiveStrong Calorie Tracker
Lose Weight. Feel Great! Change your life with MyPlate by LIVESTRONG.COM
  • Gain 2 pounds per week
  • Gain 1.5 pounds per week
  • Gain 1 pound per week
  • Gain 0.5 pound per week
  • Maintain my current weight
  • Lose 0.5 pound per week
  • Lose 1 pound per week
  • Lose 1.5 pounds per week
  • Lose 2 pounds per week
  • Female
  • Male
ft. in.


Demand Media