It is difficult to avoid the use of all prescription drugs while breastfeeding – especially if you are having multiple children and nursing for a length of time with each one. And then there are the street drugs that nobody speaks of. If you are in the habit of using these when you become pregnant, you may need assistance and some honest research to prove how harmful they can be. As with any medical questions in pregnancy and during breastfeeding, your doctor or midwife will know more about your personal history and circumstances than any website, but it is always good to gain as much knowledge as possible in order make the ultimate decision about the health of your baby. The decision to take or continue drugs should include thought on whether the substance will enter the breastmilk, whether the mother will be able to care for the infant with or without the drug, and how the drug affects the milk supply.

A quick reference guide (including common vitamins as well as prescriptions) developed with the National Health Service of the UK is very easy to read.

Excellent information on breastfeeding and drugs can also be found at

According to Motherisk,

Amphetamines have been detected in infant urine following maternal therapy. Nothing is known about maternal amphetamine abuse and its potential effect on nursing infants. Cocaine is excreted into breast milk in notable concentrations; infants might accumulate the drug because they are less able than adults to metabolize it. Cocaine has been detected in infant serum, and toxicity has been reported in some infants. Infants exposed to marijuana through breast milk showed a delay in motor development at 1 year old. Heroin toxicity has been observed in infants breastfed by mothers abusing heroin, but at therapeutic doses, most opioids, such as morphine, meperidine, methadone, and codeine, are excreted into milk in only minimal amounts and are compatible with breastfeeding. Phencyclidine, a potent hallucinogen, has been found in breast milk several weeks after maternal dosing. This is attributable to its long half-life; nursing mothers should be encouraged to avoid it.”

Cigarette smoking should be minimized while breastfeeding. While second-hand smoke exposure is probably the greater concern, smoking might decrease milk supply and nicotine can be measured in breast milk.”**

The most important thing that you can do when wondering about prescription or street drugs is to be honest with your physician, or call the Motherisk phone line at

1-877-327-4636 – Alcohol and Substance
1-800-436-8477 – Morning Sickness
1-888-246-5840 – HIV and HIV Treatment
(416) 813-6780 – Motherisk’s Home Line

** Detailed footnotes for the above Motherisk text are located on their website.

See also our article on Flu and pregnancy for more info on drugs.

-Jill Amery is the mother of two and the CEO of UrbanMommies.