Dangers of taking drugs while breastfeeding

Generally speaking, breastfeeding is considered the best way to feed a baby in the first year after birth. However, if you need to take drugs or become addicted to substances such as recreational drugs or alcohol, it may harm your body.

It is important to check with your doctor in advance about the drugs or substances you are using. Your doctor can help you decide what to do.

Factors to consider

Before prescribing medicine, your doctor will consider:

  1. How much medicine will be excreted from breast milk
  2. Risk of short-term and long-term adverse (harmful) effects on your baby

Drug excretion in breast milk and baby’s exposure

How much drug is excreted in breast milk depends on the characteristics of the drug and how the drug enters breast milk from the plasma. The ratio of breast milk to plasma drug concentration is related to the ratio of drugs in breast milk. However, this ratio will change over time, so it is not an absolute measure. In addition, other factors can affect the drug content in an individual’s breast milk.

The actual exposure level of the drug to the baby can be estimated by assuming that the baby drinks a certain amount of milk each day, but in reality, this will be different. Compared with the therapeutic dose of the drug, this also considers the infant’s “clearance rate” of the drug-the lower the clearance rate, the higher the infant’s exposure to the drug.

For most drugs, it is not known at which dose it will not affect the baby. Therefore, use 10% of the infant therapeutic dose (or the adult equivalent dose, adjusted by body weight).

If the infant receives less than 10% of the dose, drug exposure is generally considered unimportant (although there are exceptions).

Obviously, these calculations will become more difficult if you use street drugs, because the concentration of the active ingredient is largely unknown. But your doctor will be able to discuss the best course of action for you and your baby, including a safety plan to reduce and stop the medication. Below is more information about street drugs and legal and prescription drugs.

LactMed data on drugs and chemicals in breast milk

There are few studies on the risk of harmful effects of drugs in breast milk on infants. It is unethical to conduct a controlled study that could put babies at risk by deliberately administering drugs to breastfeeding mothers. However, there are some studies on babies whose mothers are already taking medications during breastfeeding.

The National Library of Medicine of the National Institutes of Health maintains a LactMed database containing the latest information on adverse drug reactions in breast milk. You can search for any drug or substance in their database. The peer review team carefully reviewed the data. The following is LactMed’s research report on some common drugs in breast milk and their risks.


Cocaine and its breakdown products enter breast milk from the mother, and babies are very sensitive to these substances. Babies exposed to cocaine through breast milk may experience extreme irritability, tremors, vomiting, and diarrhea.


The use of marijuana and cannabis products during breastfeeding raises concerns that the neurotransmitter effect of tetrahydrocannabinol (THC) can affect the child’s nervous system. A long-term study found that frequent use (every day or almost every day) may cause delays in motor development. The impact of THC on the mother may impair her judgment and ability to care for the baby.


Methadone can cause sedation, respiratory depression, and withdrawal symptoms in infants who consume methadone through breast milk. At higher doses, this is enough to cause death. However, some reports indicate that mothers may consume up to 20 mg per day while breastfeeding, while other reports recommend up to 80 mg per day. If the mother takes more than 20 mg of methadone per day, the methadone concentration in the mother’s breast milk and the baby’s blood should be monitored at the same time. Buprenorphine has been suggested as a safer alternative.


Drinking alcohol during breastfeeding is not recommended. If you successfully abstain from alcohol during pregnancy, please refrain from drinking alcohol again during breastfeeding. If you drink alcohol during pregnancy, your child is at risk of fetal alcohol spectrum disorder (FASD), so please discuss with your doctor as soon as possible to refer your child for early intervention, which may help your child’s learning and developing.

Studies have shown that babies who are breastfed after their mothers have drunk a glass or two of alcohol may experience emotional agitation, poor sleep, and reduced milk intake, while mothers may experience reduced lactation. Drinking a glass of wine or beer a day and waiting 2 to 2.5 hours before breastfeeding is considered unlikely to cause problems. Generally speaking, no matter how old you are, alcohol is harmful to your brain and body, so please keep this in mind and act responsibly.


There are many painkillers on the market, from over-the-counter drugs to prescription drugs. Some are known to increase the risk of neurobehavioral depression in infants exposed to breast milk. Discuss with your doctor the safest alternatives for you, and consider using non-drug alternatives to relieve pain, at least during breastfeeding.


Caffeine is one of our most widely accepted drugs, so there are few reports on its effects on babies. However, studies have shown that it appears in breast milk soon after the mother drinks it. With high caffeine intake, babies are irritable and have poor sleep patterns. According to LactMed, experts recommend that mothers limit their daily intake of 300 mg of caffeine. The caffeine content of beverages varies, so there may only be two to three cups of brewed coffee. Also consider soda, iced tea, and other sources.

Nicotine and smoking

If you smoke around your baby, regardless of whether you are breastfeeding or not, you increase your baby’s risk of diseases such as Sudden Infant Death Syndrome (SIDS) and asthma. It is strongly recommended to quit smoking. However, the use of nicotine patches and other such substitutes can also deliver nicotine to the baby through breast milk, and nicotine is believed to be responsible for the risk of SIDS. On the contrary, people think that bupropion is safe, otherwise the mother can quit smoking without medicine.

Final thoughts

Remember, the current recommendation is breastfeeding to give your baby the best start in life. But please be honest with yourself and see if it really provides the best start.

Discuss your alcohol and drug use in detail with your doctor, and follow their recommendations, especially those regarding detoxification.


Dangers of taking drugs while breastfeeding
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