To Your Good Health: What prompted discontinuation of fen-phen?

I’m a 71-year-old healthy female who has struggled with my weight all my life. In the ‘90s, I thought I had finally found the solution in fen-phen. It was like a miracle. It took all the nagging thoughts of food out of my brain. My question is, with all the drug ads on TV every day blithely showing the many side effects leading up to — and including — death, why can’t we use fen-phen? I worked in a hospital where a very large number of employees were taking it with great results. I never heard a hint about anything that could affect someone’s health. Also, I talked to many of the other patients at the doctor’s office where I was receiving it. Everyone was overjoyed with the results. I had no temptations and no constant yammering in my brain to eat something. As I said, it was a miracle. I felt like a normal person. So, why are all of these drug companies allowed to advertise their products, but one drug that truly worked had to get snatched away from us?

Fen-phen was a combination of fenfluramine and phentermine, which was approved for use in 1986. Approximately 18 million prescriptions were written for this medicine until 1987, when an association was made between the use of fen-phen and valve diseases of the heart.

These cases were reported with fenfluramine or with the related dexfenfluramine alone, but never with phentermine alone. Phentermine remains on the market. Approximately 150 cases were reported.

Subsequent studies estimated that seven out of 10,000 people who took fenfluramine or fen-phen for less than four months developed valve disease, while 35 in 10,000 people who took fenfluramine or fen-phen for more than four months developed valve disease. They were compared to people who either took phentermine alone or did not use a weight-loss medicine.

The U.S. Food and Drug Administration determined that the risk of valve disease — some being severe enough to prompt valve replacement surgery — was too high, so the FDA asked manufacturers to remove these drugs from the market.

I fully understand your perspective. Some people are willing to take the risk of a side effect because the benefit of the medicine is so great.

In my opinion, people should have the option of making their own decision, but in this case, the FDA felt that the risk was too high.

I have not seen a medicine for weight loss as effective as fen-phen until recently, when semaglutide (Wegovy and Ozempic) and tirzepatide (Mounjaro, not yet approved for weight loss) became available.

Just as you say, many of my patients report that they were able to easily control their eating while on these medicines, and as of the time I am writing, there have not been any serious adverse effects of taking these drugs, although there are plenty of milder effects.

However, these medicines only work when you continue to take them, and stopping them generally results in rapid regain of the weight that was lost.

It’s important to realize that if you take a weight-loss drug, you’re making a commitment to a long-term treatment.