Contact urticaria from hops in a patient with previous urticaria-angioedema from peanut, chestnut and banana.
– Contact Dermatitis 2002 Feb;46(2):127 — Contact urticaria from hops (Humulus lupulus) in a patient with previous urticaria-angioedema from peanut, chestnut and banana. — Estrada JL, Gozalo F, Cecchini C, Casquete E.

The female flowers of the hop plant are used as a preservative and as a flavoring agent in beer. However, a recurring suggestion has been that hops have a powerful estrogenic activity and that beer may also be estrogenic. There is a potent phytoestrogen in hops, 8-prenylnaringenin, which has an activity greater than other established plant estrogens. The presence of 8-prenylnaringenin in hops may provide an explanation for the accounts of menstrual disturbances in female hop workers. This phytoestrogen can also be detected in beer, but the levels are low and should not pose any cause for concern.

– J Clin Endocrinol Metab 1999 Jun;84(6):2249-52 — Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer. — Milligan SR, Kalita JC, Heyerick A, Rong H, De Cooman L, De Keukeleire D.

Hops can have a sedative effect and may interact with or increase medications.
– Z Arztl Fortbild (Jena) 1993 Apr 12;87(5):401-6 — Phytogenic sedatives-hypnotics–does a combination of valerian and hops have a value in the modern drug repertoire? — Kammerer E.

Five dogs, 4 of which were Greyhounds, suffered adverse effects secondary to the ingestion of spent hops. Mean time to onset of clinical signs was 3 hours, and clinical signs included marked hyperthermia, restlessness, panting, vomiting, signs of abdominal pain, and seizures. Four of the 5 dogs died despite aggressive therapeutic measures, and there was rapid onset of rigor mortis in 3. The overrepresentation of Greyhounds, coupled with the clinical signs, was suggestive of a malignant hyperthermia-like response to the ingestion of hops.

– J Am Vet Med Assoc 1997 Jan 1;210(1):51-4 — Malignant hyperthermia-like reaction secondary to ingestion of hops in five dogs. — Duncan KL, Hare WR, Buck WB.