Cabergoline

What cabergoline does

Prolactin is the hormone that tells the breasts to make milk, and the pituitary gland — a pea-sized gland at the base of the brain — is where it is made. When too much prolactin circulates, periods can stop or turn irregular, the breasts may leak, and getting pregnant becomes harder. Cabergoline copies dopamine, the body's own signal for switching prolactin production down. It attaches to dopamine receptors on the pituitary cells that release prolactin, so less of the hormone reaches the blood. Its work is on the pituitary, not on the ovaries or the breasts themselves.

What it treats

A blood test showing high prolactin is usually where the story starts. Cabergoline brings it down in hyperprolactinaemia (too much prolactin in the blood) and in prolactinoma, a small, usually non-cancerous growth of the pituitary that pumps out the hormone. Shrinking that growth can ease pressure symptoms such as headaches and trouble with side vision. The same tablets are used to stop milk production when there is a medical reason for it, and for high prolactin when no growth is found. Treatment tends to run for months or years, because stopping early usually lets prolactin — and a prolactinoma — build up again.

A tablet once or twice a week

Most people take cabergoline once or twice a week rather than every day, and the days stay the same from week to week — two evenings, say. Swallow a tablet with a drink; it can go with a meal or on an empty stomach. Nausea is the complaint that comes up most, and a light snack or taking the dose just before bed often takes the edge off it. What is sold here is generic Dostinex, plain tablets in 0.25mg and 0.5mg, and the strength you pick comes down to how the weekly amount divides into whole tablets. You will find it with the other hormone and fertility medicines in Women's Health.

Side effects

Feeling sick, headache, dizziness, tiredness and constipation are the ones people notice most, and they usually settle after a couple of weeks. Drowsiness is common enough that driving is best left until you know how the tablets affect you. Much less often, long-term treatment — especially at higher weekly doses — is linked to fibrosis (scarring) of the heart valves and, rarely, of the lungs or the tissue behind the abdomen; heart scans are sometimes used to look for it after several years. A few people on dopamine-type medicines find their urges change, with gambling, shopping or sex becoming hard to control; this fades when the tablets stop.

Other medicines, alcohol and storage

Antipsychotics and metoclopramide block dopamine and can cancel out cabergoline's effect. Erythromycin and similar antibiotics, and antifungals such as ketoconazole, slow the way cabergoline is broken down and can push its level up. Alcohol adds to the dizziness and nausea, particularly in the first weeks. Keep the tablets in their blister in a dry place, and give an old strip a quick look before you use it.