Primrose Oil and Warfarin

Publication Date: 
Tue, 11/08/2011
By: Alere Staff

According to the National Institutes of Health, evening primrose oil (also known as linoleic acid, night willow herb, and primrose) is used by some patients for eczema, bronchitis, diabetes, and weight loss. Primrose oil is classified as a dietary supplement; it is widely available in many pharmacy and food stores as a gel-capsule that comes in a variety of strengths. Because primrose oil is a dietary supplement, quality and purity are not regulated by the Food and Drug Administration and may vary from one manufacturer to another.

While well tolerated by most patients, primrose oil has been reported to affect platelet aggregation. This effect can lead to prolonged bleeding time and increased bleeding risk.1 More frequent testing of your INR may be necessary. As always, consult with your doctor before you start taking or stop taking supplements.

  1. Jellin JM, , et al. Pharmacist's Letter/Prescriber's Letter of Natural Medicines Comprehensive Database (7th Edition). Stockton, CA. 2005. Therapeutic Research Faculty.