Drug Information Page

Below are a few definitions and important information related to Fen Phen.

  Drug Facts  

Fen Phen – Drug made of the combination of fenfluramine and phentermine for use as an appetite suppressant in the management of obesity. Also known as Fen-Phen, PhenFen, or Phen-Fen.

Fenfluramine – Drug used as appetite suppressant for the short-term (a few weeks) management of obesity, approved by FDA in 1973. Contains dexfenfluramine and levofenfluramine.

Phentermine – Drug used as appetite suppressant for the short-term (a few weeks) management of obesity, approved by FDA in 1959.

Dexfenfluramine – Drug used as appetite suppressant for the short-term (a few weeks) management of obesity, approved by FDA in 1996. (Redux)

Levofenfluramine – Drug removed from fenfluramine (known to cause drowsiness) that created dexfenfluramine (Redux).

Why are fenfluramine and dexfenfluramine being withdrawn? – The FDA has received over 100 reports (including the original 24 Mayo cases) of heart valve disease associated mainly with fen-phen.

Why isn't phentermine being withdrawn? – No cases of heart valve disease meeting FDA's case definition have been reported with phentermine alone.

Why doesn't phentermine cause valve disease? – When the drug fenfluramine is divided to remove levofenfluramine, the dexfenfluramine that remains is serotonin-stimulating. The valve problems were of a specific type associated with serotonin levels in the brain.

What is heart valve disease? – Most commonly it's excessive tightness or leakage of the valves. Leakage is the problem associated with Fen Phen.

How do you know if you are a candidate for heart valve disease? – Your doctor may hear a heart murmur that wasn't present before or other changes noticed through an echocardiogram. If you have been taking fen-phen, ask your doctor if you should have an echocardiogram.

Are women the only candidates for heart valve disease from fen-phen? – Though the majority of cases are women, men are also at risk.

What is an echocardiogram? – An echocardiogram (echo test) is a safe test that uses ultrasound (sound waves) to evaluate the functions and flows of blood through the heart.

Is herbal fen-phen the same thing? – Herbal fen-phen does not contain either fenfluramine, dexfenfluramine, or phentermine. It is considered a "natural remedy" and isn't reviewed by the FDA.