Some antipsychotics raise blood levels of prolactin, a hormone made by the pituitary gland. When prolactin stays high for weeks or months, it can disrupt menstrual cycles, cause breast tenderness or unexpected milk production, lower libido, and over time affect bone density. The medical name for chronically high prolactin is hyperprolactinaemia. It is one of the most common — and most under-discussed — antipsychotic side effects.
Antipsychotics that strongly block dopamine D2 receptors in the pituitary often raise prolactin, which can cause sexual, menstrual, and breast symptoms — most of which are reversible.
How antipsychotics raise prolactin
Dopamine normally tells the pituitary gland to stop releasing prolactin. Antipsychotics that block dopamine D2 receptors in the tuberoinfundibular pathway remove that brake, so prolactin rises. Drugs that block D2 strongly and don't easily cross back out of the pituitary tend to raise prolactin the most.
Which medications raise it most
Based on FDA labelling and head-to-head studies including the NIMH CATIE trial and the European EUFEST first-episode study:
- High prolactin elevation: risperidone, paliperidone, haloperidol, amisulpride, sulpiride
- Moderate elevation: olanzapine, ziprasidone, lurasidone
- Minimal or no elevation ("prolactin-sparing"): aripiprazole, brexpiprazole, cariprazine, clozapine, quetiapine
Aripiprazole is unusual: as a partial dopamine agonist, it can lower prolactin and is sometimes added in low doses specifically to bring elevated prolactin down.
How common is it?
On risperidone or paliperidone, the majority of women and a substantial fraction of men develop measurably raised prolactin within weeks. Symptoms don't develop in everyone with raised levels — but when they do, they can be significant and are often left untreated because patients don't realise the link.
Symptoms to watch for
In women
- Irregular, lighter, or absent periods (oligomenorrhoea or amenorrhoea)
- Galactorrhoea — milky discharge from the nipples, sometimes only when squeezed
- Breast tenderness or enlargement
- Reduced libido, vaginal dryness
- Difficulty conceiving
In men
- Reduced libido and erectile dysfunction
- Gynaecomastia — breast tissue growth
- Galactorrhoea (less common but possible)
- Reduced facial and body hair over time
In both
Long-term high prolactin lowers oestrogen and testosterone, which over years can reduce bone density and raise fracture risk.
Getting it diagnosed
A simple fasting morning blood test measures prolactin. Normal ranges are roughly under 25 ng/mL in women and under 20 ng/mL in men, but lab cut-offs vary. Levels above 100 ng/mL on an antipsychotic are common; levels above 200 ng/mL warrant further investigation (an MRI to rule out a pituitary tumour, which is unrelated to the medication but should be excluded).
Prolactin can also rise from stress, exercise, breastfeeding, hypothyroidism, and certain other medications, so context matters.
What to do
If you have symptoms or a high prolactin level, several options are possible — all in conversation with your prescriber:
- Switch antipsychotic. Moving from risperidone or paliperidone to a prolactin-sparing agent (aripiprazole, quetiapine, clozapine) often normalises prolactin within weeks.
- Add low-dose aripiprazole. Adding 5–15 mg of aripiprazole alongside the existing medication has good evidence for lowering prolactin without losing efficacy. This is sometimes called the "aripiprazole add" and is well documented.
- Lower the dose. Sometimes prolactin elevation is dose-dependent and a careful reduction is enough.
- Treat downstream consequences. If menstrual cycles are absent for many months, hormone replacement or oral contraception may be considered to protect bone density.
When to call your prescriber
Periods that have stopped, new milk production, persistent breast pain or growth, sexual dysfunction that wasn't there before starting the medication, or any of these in combination with headaches or visual changes (which can suggest something more than antipsychotic effect).
The under-discussion problem
Studies suggest that the majority of patients on prolactin-raising antipsychotics are never asked about menstrual or sexual symptoms during routine appointments. Many tolerate symptoms for years assuming they are part of the illness or part of "what medication does." They aren't. They are usually treatable, often by a single switch or addition. Bringing them up explicitly with a prescriber is the first step.
What this means in practice
If you are starting a high-prolactin antipsychotic, ask for a baseline prolactin level. If you develop symptoms, ask for a repeat test. The numbers help guide decisions and prevent symptoms from being dismissed as "stress" or "part of the illness." See also our broader article on sexual side effects and the risperidone side effects guide.
This article is for educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a qualified mental health professional. If you or someone you know is in crisis, call or text 988 in the US, or your local emergency number.