If you are currently being treated with any of the following medications, you should not use omega-6 supplements without first talking to your health care provider.

Blood thinning medications -- Individuals taking blood thinning medications, including warfarin (Coumadin) or clopidogrel (Plavix) should not take omega-6 fatty acid supplements without consulting a health care provider. Omega-6 and omega-3 fatty acids may increase the risk of bleeding in sensitive individuals.

Ceftazidime -- Gamma linolenic acid (GLA) may increase the effectiveness of ceftazidime (an antibiotic in a class known as cephalosporins), against a variety of bacterial infections.

Chemotherapy for cancer -- GLA may increase the effects of anti-cancer treatments, such as doxorubicin, cisplatin, carboplatin, idarubicin, mitoxantrone, tamoxifen, vincristine, and vinblastine.

Cyclosporine -- Taking omega-6 fatty acids during therapy with cyclosporine, a medication used to suppress the immune system after an organ transplant, for example, may increase the immunosuppressive effects of this medication and may protect against kidney damage (a potential side effect from this medication).

Phenothiazines -- Individuals taking a class of medications called phenothiazines, including chlorpromazine (Thorazine), fluphenazine (Stelazine), perphenazine (Trilafon), promethazine (Compazine), and thioridazine (Mellaril), to treat schizophrenia should not take evening primrose oil (EPO) because it may interact with these medications and increase the risk of seizures. The same may be true for other omega-6 containing supplements.