The Side Effects of Agnus Castus

Vitex agnus castus, known as chaste tree or chasteberry, grows naturally in Mediterranean countries and central Asia. The fruit extract of agnus castus is used as an herbal remedy, according to the University of Michigan Health System (UMHS). Research indicates that it may be beneficial for premenstrual syndrome, regulating the menstrual cycle, and relieving heavy or painful menstruation. Agnus castus typically does not cause significant negative side effects.

Woman with headache. (Image: canmocan/iStock/Getty Images)

Minor Side Effects

Gastrointestinal effects are possible when taking agnus castus, as explained by the UMHS. Some people may experience gas, heartburn, upset stomach, nausea or diarrhea. Other relatively minor and uncommon side effects associated with this herb include headache, frequent urination, fatigue and agitation.

Skin Reactions

Rarely, some people may experience skin reactions to agnus castus, as noted by IntegrativePractitioner. Most of these symptoms appear to be mild allergic reactions to the herb. They include rash, hives, itchy skin, eczema and skin eruptions. An individual may develop acne or experience some hair loss while taking agnus castus, but these effects are unlikely.

Hormonal Effects

Although agnus castus does not contain hormones, it acts upon the pituitary gland and may have estrogen-like effects. The Memorial Sloan-Kettering Cancer Center cautions that patients with hormone-sensitive illnesses may not be able to safely use agnus castus. Pregnant women and women undergoing in vitro fertilization should not take this herbal remedy, according to IntegrativePractitioner. The herb may stimulate the uterus, which could lead to contractions. Women receiving hormonal therapy also should not take this herb. Hormone-related side effects associated with agnus castus are rare, but some women may develop hot flashes, breast pain, changes in the menstrual cycle, increased menstrual flow, fibroid growth, pelvic disease, weight gain or vaginitis.

Other Rare Side Effects

Agnus castus is probably safe when healthy adults take it in recommended doses for short-term relief of symptoms, according to IntegrativePractitioner. There are rare reports of vertigo, drowsiness, nosebleed, sweating, dry mouth, depressed mood, increased eye pressure, rapid heart rate, palpitations and seizure.