In one human study, allergic reactions were reported in 2% of patients and treatment was stopped in one case due to throat swelling and shortness of breath. It is not clear which ingredient in PC-SPES® might have been responsible. Products containing herbs similar to PC-SPES® should be avoided by people with allergies to any of the included herbs.
PC-SPES® has been recalled and should not be used. Undeclared prescription drug ingredients have been found in samples of PC-SPES®, including indomethacin, diethystilbesterol (DES), ethinyl estradiol, and warfarin.
PC-SPES® may increase the risk of blood clots. Several cases of blood clots, including life-threatening clots to the lungs, have been reported with PC-SPES® use. In contrast, cases of bleeding have also been reported. These are theorized to be due to undeclared amounts of the prescription drug warfarin in some samples of PC-SPES®, or to the presence of the PC-SPES® ingredient saw palmetto, which is associated with one report of bleeding. This would add to the risk of bleeding in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. The bleeding disorder disseminated intravascular coagulation (DIC), which can include clotting, bleeding, or both, has also been reported.
Adverse effects associated with undeclared prescription drug ingredients in PC-SPES® are possible, such as gastrointestinal distress from indomethacin.
PC-SPES® has not been evaluated during pregnancy or breastfeeding and should be avoided. Estrogenic-effects may be harmful. The undeclared prescription drug DES, discovered in some samples of PC-SPES®, may increase the risk of reproductive tract abnormalities in daughters born to women taking this drug.
Based on reported cases of bleeding and inclusion of undeclared amounts of the prescription blood-thinner warfarin in some samples, PC-SPES® may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®). In contrast, PC-SPES® has also been associated with an increased risk of blood clots, which may be due to estrogen-like effects. This would work against the action of blood-thinning medications.
Based on the proposed anti-androgenic mechanism of action of saw palmetto, a major ingredient of PC-SPES®, additive effects may occur with anti-androgen drugs such as the 5α-reductase inhibitor finasteride (Proscar®); the androgen receptor antagonists bicalutamide (Casodex®), flutamide (Eulexin®), and nilutamide (Nilandron®); or the GnRH antagonists leuprolide (Lupron®), goserelin (Zoladex®), and histrelin (Supprelin®). Similarly, this therapy may decrease the effectiveness of therapeutic androgens such as testosterone (Androderm®, Testoderm®), methyltestosterone (Android®, Testred®, Virilon®), fluoxymesterone (Halotestin®), nandrolone decanoate (Deca-Dubrolin®), or stanozolol (Winstrol®).
PC-SPES® may add to the estrogenic effects of other drugs, based on estrogen-like effects reported in studies, and the presence of undeclared amounts of prescription estrogen drugs in some samples of PC-SPES®.
Based on reported cases of bleeding and inclusion of undeclared amounts of the prescription blood-thinner warfarin in some samples, PC-SPES® may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases. In contrast, PC-SPES® has also been associated with an increased risk of blood clots, which may be due to estrogen-like effects. This would work against the action of blood-thinning agents.
PC-SPES® may add to the estrogenic effects of other agents based on estrogen-like effects reported in studies and the presence of undeclared amounts of prescription estrogen drugs in some samples.
PC-SPES® may affect the way the liver breaks down certain herbs and supplements.