| | What Are These Diet Drugs? : The combination use of Fenfluramine and phentermine and with dexfenfluramine is not approved by the United States Food and Drug Administration (FDA), but was not illegal when these drugs were on the market. Doctors are generally permitted to make "off-label" or non-approved uses of drugs if the drugs are approved for any use.Symptoms Of Injury From Fen-Phen, Redux Or Pondimin Use: Usually the first symptom of injury from these diet drugs is shortness of breath. Medically shortness of breath is called dyspnea | | | |