Question: I had a hysterectomy for endometrial stromal sarcoma and was told not to take hormones afterward. But is it OK to take 650 mg of quercetin for my hayfever? I have read that quercetin acts like estrogen.

Dr. Hibberd's answer:
Quercetin acts like an antihistamine and an anti-inflammatory, and may help protect against heart disease and cancer in addition to relief of symptoms of hay fever. Quercetin stabilizes the cells that release histamine in the body and thereby have an anti-inflammatory effect. A recent animal study has found that quercetin may exacerbate estrogen (E(2))-induced breast tumors. On the other hand, other studies have concluded that quercetin is an anti-cancer agent. With conflicting reports, why not try to take a treatment other than quercetin for your hay fever?
Hay fever symptoms can be treated effectively with antihistamines. For symptoms that aren't too severe, many medicines are available over the counter. Examples you could try include loratadine (Claritin, Alavert) and cetirizine (Zyrtec). Fexofenadine (Allegra) is available by prescription. The prescription antihistamine nasal sprays azelastine (Astelin, Astepro) and olopatadine (Patanase) can relieve nasal symptoms. Olopatadine eyedrops (Patanol, Pataday) help relieve eye itchiness and eye irritation caused by hay fever. Other prescription medications are available which can be suggested by your doctor for your hay fever symptoms.