Hyperlactation syndrome (HS), or “oversupply,” occurs when a person produces more breast milk than their baby requires. This can cause symptoms such as breast pain or discomfort, leakage, and blocked milk ducts.

Hyperlactation can also cause problems for the baby, including choking, excessive weight gain, and digestion issues.

This article examines some reasons hyperlactation occurs, symptoms of hyperlactation, techniques for managing milk oversupply, and more.

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Lactation starts during pregnancy when hormonal shifts prompt the mammary glands to produce and release milk, preparing for the baby’s arrival.

Once the infant is born, milk production increases. As the baby begins feeding regularly, the person’s body will adjust milk production to match the baby’s needs.

However, sometimes, a person continues producing an increased amount of breast milk, resulting in more milk than the baby needs — a milk oversupply. This is hyperlactation.

While it is difficult to know how many people experience hyperlactation, the condition is not unusual.

Nevertheless, overproduction of breast milk is typically frustrating, uncomfortable, and even painful at times for both the feeder and the baby.

Learn more about breastfeeding or chestfeeding.

Aside from excessive breast-milk production, someone with HS may experience:

Infants can also experience symptoms related to the oversupply of breast milk, including:

  • difficulty latching
  • choking or gagging during feeding
  • “fussiness” during or after feeding
  • excessive spitting up or vomiting after feeding
  • gassiness or abdominal discomfort
  • green, frothy, or explosive bowel movements
  • rapid weight gain or difficulty maintaining a consistent weight

According to the charity La Leche League, some people naturally produce large quantities of milk, and it is common for the amount to increase with each baby.

Some factors that can cause or contribute to HS include:

  • nursing to a set schedule rather than when the baby is hungry
  • overexpressing the breasts, such as pumping too much or too often, as this will stimulate milk production
  • difficulty latching, which can cause the baby to feed more frequently to ensure they get the appropriate amount of breast milk

Rarely, HS may occur due to an underlying medical condition, such as a genetic predisposition or hyperprolactinemia, which is an excess of the hormone prolactin in the blood.

The United Kingdom’s National Childbirth Trust (NCT) recommends that people follow the tips below if they are experiencing HS beyond 6–8 weeks:

  • checking the baby is latching well at the breast
  • leaning back when feeding to help slow the flow of breast milk
  • gradually reducing or stopping expressing, as this can worsen HS
  • block feeding the baby, which involves only offering only one breast during a feed and changing sides every 2–3 hours
  • seeking advice from a professional, such as a midwife or a certified lactation consultant

La Leche League recommends some additional tips to help manage HS. These include:

  • Responsive feeding: Allow the baby to nurse whenever they show hunger cues. Allow the baby to feed at the first breast for as long as they want and then offer the second side. During a feed, the baby might want one or both sides or want to switch between sides more than once. These are all typical patterns for a feed.
  • Various positions: Try feeding in different positions, such as side lying or having the baby sit upright.
  • Hand expression: Hand express a very small amount of milk before latching the baby.
  • Breast massage: Gently massage the breast for around 30 seconds before feeding.
  • Full drainage: This method may be best for people experiencing recurrent blocked ducts, mastitis, or breast discomfort. A person should only do this in consultation with a lactation specialist and usually only needs to be done once. It involves the following steps:
    • Step 1: Express milk from both breasts to “empty” them as much as possible.
    • Step 2: Immediately offer both breasts to the baby after “emptying.”
    • Step 3: Block feeding.
  • Medications and herbs: A person can talk with a lactation consultant about medications and herbs they can take to help reduce milk production.

The NCT notes that HS can occasionally indicate an underlying medical condition. As such, anyone who experiences continued HS despite trying the above treatments should consider contacting a doctor to determine the cause.

According to the NCT, most cases of HS resolve once a person’s milk supply regulates to match their baby’s needs.

However, if HS continues despite the home treatments outlined above, a person should consider contacting a doctor for further advice. In a small number of cases, HS can be due to an underlying medical condition.

Hyperlactation can occur in females who are not pregnant and males. Medical professionals refer to this as “galactorrhea.”

There are two main causes of galactorrhea: hypothalamic-pituitary (HP) and nonhypothalamic-pituitary (non-HP).

HP causes of hyperlactation

Hypothalamic-pituitary causes involve parts of the brain called the hypothalamus and pituitary gland.

These areas secrete various hormones and play a major role in the functioning of the hormonal and nervous systems.

Potential HP causes of galactorrhea include:

  • Prolactinomas: These are pituitary tumors that secrete the hormone prolactin. This hormone is responsible for breast development, lactation, and other various bodily functions.
  • Other types of pituitary tumor: Some pituitary tumors can compress the pituitary stalk — a connection between the hypothalamus and pituitary gland. This can disrupt the flow of a neurochemical called dopamine and, in turn, decrease the inhibition of prolactin, resulting in mild galactorrhea.

Non-HP causes

Some non-HP causes of galactorrhea include:

  • Hypothyroidism: Elevated levels of the thyroid hormone — thyrotropin-releasing hormone (TRH) — can stimulate cells that release prolactin.
  • Kidney failure: This condition impairs the kidneys’ ability to clear prolactin.
  • Chest wall lesions: Scientists have found an association between chest wall lesions and galactorrhea. This may happen when pain signals traveling from the chest wall reach the hypothalamus, decreasing dopamine release.
  • Certain medications: Some medications that may trigger galactorrhea include:

Below are some answers to common questions about hyperlactation syndrome (HS).

How do you treat hyperlactation syndrome?

Treatments for HS aim to reduce the overproduction of breast milk. Examples include responsive feeding, ensuring a proper latch, and reducing or stopping expressing. A person can also try massaging the breasts before feeding, fully draining the breasts before offering both to the baby, and block feeding.

What causes hyperlactation?

Factors that can cause or contribute to hyperlactation include difficulty latching, overexpressing the breasts, or feeding to a schedule. An underlying medical condition, such as hyperprolactinemia, can also cause hyperlactation.

What are the risks of hyperlactation?

Hyperlactation can lead to complications, such as blocked milk ducts or mastitis. Babies may also choke or gag on the breast milk, excessively spit up or vomit during or after eating, or have explosive bowel movements.

Hyperlactation also makes it difficult to maintain a healthy feeding schedule and can cause digestion issues, gastrointestinal problems, and rapid weight gain in babies.

However, most cases of HS resolve once a person’s milk supply regulates to match the baby’s needs. This typically takes several weeks after the baby is born.

HS occurs when a person who is breastfeeding or chestfeeding produces an excessive amount of breast milk.

Symptoms include engorgement, leaking, and difficulty regulating the milk supply. Management usually involves adjusting feeding techniques and, in persistent cases, medication.

In a small number of cases, HS can be due to an underlying medical condition. Anyone who continues to experience issues with HS following the home treatments outlined above should consider contacting a doctor to determine the cause.