A Mediterranean fruit extract that lowers the milk-producing hormone prolactin. Evidence is strongest for premenstrual symptoms and monthly breast pain, thinner for cycle length and second-half hormone patterns, early for fertility, menopause and metabolic health. Reported problems are mild and reversible. Most trials came from the two companies making the extracts, and the effect size is probably overstated. (Full Review)

Protocol

Standard European protocol

20 mg daily

Standardized dry fruit extract Ze 440, or 4 mg of the 10:1 extract BNO 1095, taken continuously for at least three menstrual cycles.

Best time of day

Morning, on rising

A single morning dose. Prolactin output peaks during sleep and early morning, so morning dosing places the effect where the target signal is highest.

Baseline biomarkers

Measured before starting

Prolactin, mid-luteal progesterone and thyroid-stimulating hormone. Normal prolactin does not preclude a trial, but it lowers the prior probability of a genuine drug response.

Time to effect

Premenstrual symptoms

3 cycles

Partial relief appears within the first cycle; the full effect requires three.

Cyclical breast pain

3 cycles

Pain intensity was measured after three cycles; trials stopping at one cycle understate benefit.

Cycle regulation

Up to 6 months

Cycle-regulating effects can take up to six months to stabilize.

Benefits

High: Relief of premenstrual syndrome symptoms; reduction of cyclical breast pain

Medium: Correction of latent hyperprolactinemia and short luteal phase

Low: Relief of menstrual pain and cycle irregularity; improvement of metabolic and oxidative markers in polycystic ovary syndrome

Speculative: Relief of perimenopausal symptoms; support of fertility in luteal phase deficiency; improvement of sexual function

Contraindications

Pregnancy at any stage

Breastfeeding

Estrogen-sensitive cancers (breast, endometrial, ovarian; active or in remission)

Prolactin-secreting pituitary tumor larger than 10 mm, or any tumor requiring drug therapy

Active ovulation-induction or in vitro fertilization cycle, and at least four weeks beforehand (clomiphene, letrozole, injectable gonadotropins)

Adolescents under 18 outside specialist supervision

Antipsychotic treatment where prolactin elevation forms part of therapeutic monitoring

Key Interactions

Dopamine-blocking prescription drugs (antipsychotics such as haloperidol, risperidone, amisulpride; the anti-nausea drug metoclopramide)

Dopamine agonists (bromocriptine, cabergoline)

Combined oral contraceptives and menopausal hormone therapy

Over-the-counter agents (cimetidine; sedating antihistamines with dopamine-blocking activity, such as promethazine)

Supplements with additive dopaminergic or prolactin-lowering effect (Mucuna pruriens; high-dose vitamin B6, also called pyridoxine; zinc)

St. John's wort (Hypericum perforatum), commonly co-formulated with chaste tree

Other interventions (dopamine-active recreational and cognition-enhancing compounds; prolactin-raising opioid analgesics)

Risk & Side Effects

High: Gastrointestinal upset and nausea; headache and fatigue

Medium: Menstrual cycle disturbance and intermenstrual bleeding; acne

Low: Hypersensitivity skin reactions; masking of an underlying prolactin-secreting pituitary tumor; multiple follicular development with concurrent fertility treatment

Speculative: Loss of effect from dopamine-blocking medication; stimulation of hormone-sensitive tissue

Monitoring

Marker	Target	Why
Prolactin	5–15 ng/mL	Primary mechanistic target; identifies likely responders
Progesterone (mid-luteal)	Above 10 ng/mL	Confirms ovulation and adequate luteal function, the endpoint chaste tree is meant to restore
Thyroid-stimulating hormone (TSH)	0.5–2.0 mIU/L	An underactive thyroid raises prolactin and mimics the picture chaste tree is used for
Estradiol (early follicular)	25–75 pg/mL	Frames the estrogen-to-progesterone balance that premenstrual symptoms track
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)	LH-to-FSH ratio below 2:1, with FSH below 10 mIU/mL early in the cycle	Distinguishes polycystic ovary syndrome and the menopausal transition, both of which change the expected response
Alanine aminotransferase (ALT)	Below 25 U/L in women	Provides a reference value; no liver toxicity is known, but botanical product purity varies
Ferritin (the stored form of iron)	50–100 ng/mL	Heavy or irregular bleeding, a common reason for starting the herb, depletes iron stores

Cadence: Baseline before starting; repeat prolactin and mid-luteal progesterone after three cycles and again at six months if continued, then every six to twelve months. New spotting, a sustained shift in cycle length, or breast change warrants earlier retesting.

Qualitative Assessment

Premenstrual symptom diary: Irritability, mood, anger, headache, bloating and breast fullness rated daily; a 50% fall in the total score across three cycles is the responder definition.
Breast comfort: Days per cycle with breast tenderness and its peak intensity on a 0–10 scale, the most mechanistically responsive symptom.
Cycle regularity: Cycle length and bleeding days logged; a stable 26–32 day cycle with a luteal phase of at least eleven days is the practical target.
Sleep quality: Whether premenstrual sleep disruption resolves, since disrupted sleep is both a symptom and a driver of the nocturnal prolactin surge.
Energy and cognitive clarity: Whether the premenstrual dip in energy and concentration narrows.
Skin: Whether cyclical acne improves or worsens, because the direction is individual and cannot be predicted in advance.

Chaste Tree for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment