Fen-phen: The Birth and Death of a Dangerous Diet Fad

There are more than 1.46 billion overweight people in the world, according to the Oversases Development Institute, a think tank dedicated to international and humanitarian issues (odi.org), and the majority of them are in the U.S. Even though Americans are growing larger, it seems they'll do just about anything to lose weight. They spend an estimated $60 billion per year on diet programs and products, making it seriously big business. Spending has doubled since 1992, when the fen-phen scandal began, and diet drugs are still a hot commodity, despite repeated discussions of their lack of effectiveness or the danger involved in taking them. If you've been tempted to forgo losing weight in a natural healthy way in lieu of a quick fix diet pill miracle, you may want to learn more about one of the first diet pills to sweep the country.

The "fen-phen"omenon

Fen-phen is an anti-obesity drug that was featured on the September 1996 cover of Time Magazine and touted as "the hot new diet pill." It combined fenfluramine, a drug that provided temporary weight loss, with phentermine, a psychostimulant similar to amphetamine that suppressed the appetite. Both fenfluramine and phentermine were individually approved by the Federal Drug Administration (FDA) for short-term use in the medical management of obesity, which also includes diet, exercise and behavior modification.

The fen-phen fiasco

A 1997 article by New York Times medical reporter Gina Kolata details the rise and fall of fen-phen, the "magic pill for the national epidemic of obesity" that turned into a nightmare (nytimes.com). The timeline of the drug's downfall follows a sharp trajectory.


Dr. Michael Weintraub, then a professor of clinical pharmacology at the University of Rochester, posits trying fenfluramine and phentermine in combination. He conducts a four-year study of the drug using 121 obese patients.


Dr. Weintraub publishes his findings, and fen-phen is unleashed on the public, with doctors and fen-phen mills prescribing the drug combination to more than 6 million patients.


Wyeth-Ayerst Laboratories/Interneuron Pharmaceuticals appeals to the FDA to allow them to market dexfenfluramine, a more effective form of fenfluramine, for long-term use for weight loss.


After initially voting not to approve the drug and after much debate about the health risks of pulmonary hypertension versus the health risks of obesity, the FDA final agrees to approve the drug in early 1996. Later in the year, the Mayo Clinic reports serious heart valve abnormality in 24 women taking fenfluramine or dexfenfluramine.


  • February: A Massachusetts woman, Mary Linnen, dies of pulmonary hypertension 10 months after she began taking fen-phen, which she only took for 23 days. Her family files a wrongful death lawsuit, the first related to fen-phen.
  • July: The FDA issues a Public Health Advisory warning that 33 cases of valvular heart disease have been reported in fen-phen and dexfenfluramine users (fda.gov, 1997). The report further states there is "no conclusive evidence establishing a causal relationship between these two products and valvular heart disease." It further reiterates that the FDA never approved the long-term use of either drug individually or the use of the two drugs in combination.
  • August: The FDA issues a Public Health Advisory warning that 82 cases of heart disease have been reported but continues to assert that no causal relationship exists between fen-phen and heart disease.
  • September:The FDA issues an Advisory recommending that anyone taking fen-phen, fenfluramine or dexfenfluramine should consult a physician and stop taking the drugs immediately.

And in a few quick months, the "miracle" drug was no more.

Are there any FDA-approved weight loss drugs?

Since the fen-phen debacle, the FDA didn't approve any long-term weight loss drugs until 2012, when it approved Qsymia (Vivus Pharmaceuticals) and Belviq (Arena Pharmaceuticals), according to WebMD (webmed.com). Both drugs are approved for those termed medically obese or those who are overweight with an added weight-related health problem and should be used as a component of a weight management program that includes a reduced calorie diet and increased physical activity.

Qsymia is a combination of phentermine (the non-lethal half of fen-phen) and topiramate, a drug that increases the feeling of fullness, increases calorie burning, and makes food taste less appealing, according to WebMD.

  • The average cost of Qsymia is $160/month (webmd.com)
  • Estimated average weight loss over a year's time is 9 percent

Belviq works by turning on a switch in the brain that increases serotonin levels, which is believed to reduce appetite and increase feelings of satisfaction. For a time, Belviq was currently pending classification as a Schedule IV controlled substance by the Drug Enforcement Agency, but as of summer 2013, it was available to the public.

  • It is estimated that Belviq will cost $225-$250/month (seekingalpha.com)
  • Estimated average weight loss over a year's time is 3 to 3.7 percent

Both drugs require a prescription and both carry some health risks. FDA approval was given for the drugs because most advisory members see untreated obesity as the higher health risk. Experts report that sales of Qsymia have been slow due in part to the high cost of the drug and the fact that most health insurance does not cover it.

Before embarking on a weight loss drug regimen, carefully consider all your weight loss options and discuss them with your doctor and a nutritionist knowledgeable in weight loss nutrition. Given the dark history of anti-obesity medication, perhaps slow and steady is the way to go.


"Belviq," Eisai Inc., 2013, http://us.eisai.com/product.asp?ID=290&utm_source=google&utm_medium=cpc&utm_term=+belviq&utm_campaign=Efficacy%2B&%2BPI

"Belviq, Qsymia: New Weight Loss Drugs Compared," WebMD, 2012, http://www.webmd.com/diet/news/20120718/qsymia-belviq-new-weight-loss-drugs-compared

"Does increasing serotonin help with weight loss?," Live Strong, 2011, Livehttp://www.livestrong.com/article/375708-does-increasing-serotonin-help-with-weight-loss/#ixzz2NvrXGoP5

"FDA Doc Claims Fen-Phen Cover-up," CBS Evening News, 2009, http://www.cbsnews.com/8301-18563_162-181616.html

"Fen-phen Nation," PBS Frontline, 2003, http://www.pbs.org/wgbh/pages/frontline/shows/prescription/hazard/fenphen.html

"Fen-Phen Safety Update Information," U.S. Food and Drug Administration, 1997, http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm072820.htm

"Fen-Phen Update (Fenfluramine, Phentermine, Dexfenfluramine)," U.S. Federal Drug Administration, 1997, http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm180082.htm

"Future Diets: Implications for Food and Agriculture Prices," Sharada Keats and Steve Wiggins, Overseas Development Institute, January 2014,

"How Fen-Phen, A Diet `Miracle,' Rose and Fell," The New York Times, 1997, http://www.nytimes.com/1997/09/23/science/how-fen-phen-a-diet-miracle-rose-and-fell.html?pagewanted=all&src=pm

"Is Arena's Belviq Priced Right?," Seeking Alpha, 2013, http://seekingalpha.com/article/1222611-is-arena-s-belviq-priced-right

"New Diet Pills Raise Old Safety Questions," The New York Times, 1996, http://www.nytimes.com/1996/02/21/us/new-diet-pills-raise-old-safety-questions.html?pagewanted=all&src=pm

"Qsymia gaining traction," WebMD, 2012, http://www.webmd.com/diet/news/20121224/qsymia-gaining-traction

"Questions and Answers about Withdrawal of Fenfluramine (Pondimin) and Dexfenfluramine (Redux), U.S. Federal Drug Administration, 1997, http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm180078.htm

"Reports Of Valvular Heart Disease In Patients Receiving Concomitant Fenfluramine And Phentermine," U.S. Federal Drug Administration, 1997, http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafetyInformationforHeathcareProfessionals/PublicHealthAdvisories/ucm180072.htm

"Weight-loss pill Belviq is now available, but we say skip it," Consumer Reports News, June 13, 2013,

About the Author:
Kay Easton graduated from the State University of New York with a BA in English Literature. As a freelance and technical writer with more than 20 years experience, she writes articles for the Internet on a variety of topics.