What drugs cause lactation? A pharmacological deep dive

October 8, 2025 •

5 min read

According to the American Academy of Family Physicians, pharmacologic agents are a common cause of galactorrhea, or inappropriate lactation. This unusual side effect can be distressing and is often the result of medication-induced hormonal changes. It is vital to understand what drugs cause lactation to better identify and manage this condition.

Quick Summary

An array of medications, including antipsychotics, antidepressants, and certain anti-nausea drugs, can induce lactation by altering hormone levels. The primary cause is often the blocking of dopamine receptors, which increases prolactin secretion. Understanding the specific culprits and their mechanisms is key to diagnosis and appropriate medical consultation.

Key Points

Dopamine's Role: Many drugs cause lactation (galactorrhea) by blocking dopamine receptors, which normally suppress the release of prolactin, the milk-producing hormone.
Antipsychotics: Medications like risperidone and older 'typical' antipsychotics are major culprits due to their potent dopamine-blocking action, frequently leading to elevated prolactin levels.
Anti-Nausea Drugs: Gastrointestinal prokinetic agents like metoclopramide and domperidone (not U.S. FDA-approved) are known to cause lactation by increasing prolactin.
Antidepressants: Certain antidepressants, including SSRIs (e.g., escitalopram, paroxetine) and TCAs, can cause galactorrhea, though less commonly than antipsychotics.
Antihypertensives and Other Drugs: Some blood pressure medications (e.g., methyldopa) and H2 blockers (e.g., cimetidine) can also trigger this side effect.
Management: Consult a doctor if you experience drug-induced lactation. They may adjust your dosage, switch your medication, or prescribe a dopamine agonist to manage the symptoms.
Reversibility: In many cases, drug-induced galactorrhea is reversible upon discontinuation or adjustment of the causative medication.

The Mechanism Behind Drug-Induced Lactation

Lactation, or milk production, is primarily controlled by the hormone prolactin, which is released by the anterior pituitary gland. The secretion of prolactin is regulated by the hypothalamus, a region of the brain that produces a hormone called dopamine. Under normal circumstances, dopamine acts as a prolactin-inhibiting factor, meaning it prevents the pituitary gland from releasing excessive amounts of prolactin.

The Role of Dopamine and Prolactin

Many medications that cause lactation do so by interfering with this delicate balance. By blocking dopamine receptors, these drugs effectively remove the 'brake' on prolactin production, leading to a surge in serum prolactin levels, a condition known as hyperprolactinemia. This hormonal imbalance can trigger the mammary glands to produce milk, even in individuals who are not pregnant or breastfeeding, and can affect both women and men.

Some drugs can also increase prolactin levels through other mechanisms, such as stimulating serotonergic pathways or influencing other prolactin-releasing factors. In some rare cases, galactorrhea can occur even with normal prolactin levels, suggesting that other factors, such as increased breast tissue sensitivity, might be involved.

Major Drug Classes That Cause Lactation

Several classes of medications are known to cause or contribute to inappropriate lactation. These range from psychiatric medications to treatments for gastrointestinal issues and hypertension.

Antipsychotics

Antipsychotics are among the most common causes of drug-induced galactorrhea because many are potent dopamine receptor blockers. The risk varies among different agents.

Risperidone: This atypical antipsychotic is frequently associated with elevated prolactin levels and galactorrhea. Studies have shown a significant risk of hyperprolactinemia, which can lead to breast enlargement (gynecomastia) in men and lactation in both sexes.
First-generation (typical) antipsychotics: These older medications, such as haloperidol and chlorpromazine, are known for their strong dopamine-blocking effects and thus a high propensity for causing galactorrhea.
Amisulpride: Used in some countries, this antipsychotic also significantly increases prolactin levels.

Antidepressants

While less common than with antipsychotics, some antidepressants can cause galactorrhea, especially at higher doses.

Selective Serotonin Reuptake Inhibitors (SSRIs): Drugs like escitalopram, paroxetine, and sertraline have been linked to galactorrhea in case reports. The mechanism is thought to involve serotonin's influence on prolactin-regulating pathways.
Tricyclic Antidepressants (TCAs): Some TCAs, such as imipramine, can also cause this side effect, potentially by blocking dopamine's action indirectly.

Gastrointestinal Agents

These medications are designed to increase gastrointestinal motility but can have an off-target effect on prolactin release.

Metoclopramide: Widely used as an anti-nausea agent, metoclopramide is a known dopamine receptor antagonist and is even used off-label as a galactagogue (a substance to increase milk supply). Its side effects include elevated prolactin and galactorrhea.
Domperidone: Available in many countries outside the U.S. (where it is unapproved), domperidone also blocks dopamine receptors and is used off-label to aid lactation. It is often preferred over metoclopramide in some regions due to a lower risk of certain neurological side effects.
H2 Blockers: Cimetidine (Tagamet) has been shown to increase prolactin secretion and can cause galactorrhea, while other drugs in this class, like ranitidine, have also been implicated.

High Blood Pressure Medications

Some antihypertensive drugs can also disrupt the dopamine-prolactin axis.

Methyldopa: This older blood pressure medication works by reducing catecholamine levels and can increase serum prolactin, leading to galactorrhea.
Reserpine: Another antihypertensive that depletes dopamine and can cause galactorrhea.
Verapamil: This calcium channel blocker can also lead to hyperprolactinemia.

Opioids and Other Substances

Opioids, cannabis, and other substances can also interfere with dopamine regulation.

Opioids: Acting on mu-opioid receptors can decrease hypothalamic dopamine release and elevate prolactin levels.
Herbal Supplements: Herbal products like fennel and fenugreek have historically been used to promote lactation and can have this effect.

Comparison of Drugs and Their Lactation Risk


Drug Class	Examples	Primary Mechanism	Lactation Risk	Special Considerations
Antipsychotics	Risperidone, Haloperidol	Strong D2 receptor blockade leading to hyperprolactinemia	High	Dose-dependent, especially high with Risperidone
Gastrointestinal Agents	Metoclopramide, Domperidone	D2 receptor blockade to increase motility, but also increases prolactin	Moderate to High	Often used off-label as a galactagogue
Antidepressants	SSRIs (Escitalopram, Paroxetine), TCAs	Serotonergic pathways or indirect dopamine inhibition	Low to Moderate	Risk is lower than with antipsychotics, but still possible
Antihypertensives	Methyldopa, Verapamil	Central nervous system effects, affecting dopamine and prolactin	Low to Moderate	Older medications, sometimes still used for specific conditions
H2 Blockers	Cimetidine	Histamine H2 receptor antagonism	Low to Moderate	Some can stimulate prolactin release; cimetidine is a known example

How to Manage Drug-Induced Galactorrhea

If you suspect a medication is causing inappropriate lactation, it is crucial to consult a healthcare professional. Do not stop taking a prescribed medication on your own. A doctor can evaluate your situation and determine the appropriate course of action, which may include:

Dosage Adjustment: For some medications, lowering the dose may be enough to resolve the symptoms while still treating the underlying condition. For example, spironolactone-induced gynecomastia can sometimes regress with a lower dose.
Medication Switch: A doctor might recommend switching to an alternative medication within the same class that has a lower risk of causing galactorrhea. For example, some atypical antipsychotics like aripiprazole have a lower propensity for elevating prolactin compared to risperidone.
Adding a Dopamine Agonist: In cases where the medication cannot be changed, a dopamine agonist like bromocriptine or cabergoline may be prescribed to suppress prolactin secretion.
Managing Underlying Conditions: The doctor will also rule out other causes of hyperprolactinemia, such as thyroid disorders or pituitary tumors, with a comprehensive evaluation.

Conclusion: What Drugs Cause Lactation?

In conclusion, a variety of medications can lead to inappropriate lactation by causing hyperprolactinemia, often by blocking the dopamine receptors in the pituitary gland. Antipsychotics, anti-nausea medications like metoclopramide, certain antidepressants, and some blood pressure medications are all known culprits. While not typically a life-threatening condition, drug-induced galactorrhea can be distressing and indicates a need for medical review. It is essential to consult a healthcare provider for a proper diagnosis and management plan, which may involve adjusting the dose, switching to an alternative medication, or treating with a dopamine agonist to resolve symptoms effectively.

For more information on the evaluation and management of galactorrhea, consult authoritative medical guidelines such as those from the American Academy of Family Physicians (AAFP).

Frequently Asked Questions

Medications typically cause inappropriate lactation by increasing the amount of prolactin in the blood. Prolactin is the hormone that stimulates milk production. Many drugs, especially antipsychotics, block the action of dopamine, a neurotransmitter that normally suppresses prolactin release from the pituitary gland. Removing this inhibitory effect leads to hyperprolactinemia, which can trigger milk production.

Yes, drugs that elevate prolactin can cause lactation and breast enlargement (gynecomastia) in men. Risperidone, for example, is well-documented for causing elevated prolactin levels and gynecomastia in male patients.

Drug-induced galactorrhea is often benign and reversible. However, it can sometimes mask more serious underlying conditions, such as a pituitary tumor, and requires medical evaluation to confirm the cause. It is important to consult a healthcare professional for diagnosis and appropriate management.

Certain antidepressants, including selective serotonin reuptake inhibitors (SSRIs) like escitalopram, paroxetine, and sertraline, have been reported to cause galactorrhea. Tricyclic antidepressants have also been implicated. The risk is generally lower than with antipsychotics but is still possible.

Yes, some medications used to treat high blood pressure, such as methyldopa and verapamil, can cause galactorrhea by affecting the regulation of prolactin. This is a known side effect that warrants medical attention if it occurs.

If you notice unexpected lactation, do not stop your medication abruptly. You should immediately contact your prescribing healthcare provider. They will evaluate your symptoms, determine if the medication is the cause, and discuss appropriate steps, which could include adjusting the dose, switching to an alternative drug, or prescribing another medication to manage prolactin levels.

Yes, other causes include pituitary tumors (prolactinomas), thyroid disorders, chronic kidney disease, excessive breast stimulation, and chest wall injuries. A thorough medical evaluation by a doctor is essential to distinguish between drug-induced causes and these other potential conditions.