Phenylpropanolamine

Phenylpropanolamine, commonly abbreviated as PPA, is a synthetic sympathomimetic amine that was used in pharmaceutical products as a decongestant and, in some formulations, as an appetite suppressant. It belongs to the class of phenethylamines and was found in various over-the-counter cold and flu remedies as well as weight-loss products.

Pharmacology and use: PPA exerts its effects by stimulating adrenergic receptors, producing vasoconstriction that reduces nasal swelling and congestion. It also has central nervous system activity that contributed to appetite suppression in some weight-control regimens. Its actions are related to other phenylephrine- and ephedrine-like compounds, but its potency and safety profile differed among formulations.

Safety and regulatory history: Concerns about safety led to significant regulatory action. In the late 1990s and early 2000s, studies associated phenylpropanolamine with an increased risk of hemorrhagic stroke, particularly in women. In 2000, the U.S. Food and Drug Administration advised manufacturers to withdraw PPA-containing over-the-counter products from the market. By the following years, PPA had been largely removed from U.S. OTC decongestants and diet aids. Some other countries imposed ongoing restrictions or bans, while certain formulations and restrictions persisted in different markets.

Current status: In the United States, phenylpropanolamine is no longer approved for OTC use, and products containing PPA have been withdrawn from sale. In other countries, regulatory decisions vary, but safety concerns have led many manufacturers to discontinue PPA-containing products. Researchers continue to review its risk–benefit profile relative to alternative decongestants and appetite suppressants.