When you’re breastfeeding, you know that what you eat and drink can pass into your breast milk. But what about over-the-counter (OTC) medicines? Is it safe to take something to help a headache or to ease indigestion?

First and foremost, talk to your doctor or healthcare provider before taking any OTC medicines while breastfeeding. In general, I tell my patients that if a medicine was safe to take during pregnancy, it can be taken while breastfeeding. Only a very small amount of the medicine ends up in the breast milk — less than one percent of the dosage taken by the mother. In such small amounts, most medicines are harmless to the baby.

Still, most doctors in general, myself included, like to err on the side of caution. For this reason, I advise my breastfeeding patients to take medication only when needed. If you feel that an OTC medicine can help you feel better, talk to your doctor about it.

Here are a few rules I recommend following when taking OTC medicines while breastfeeding:

• Avoid aspirin Don’t take any aspirin or aspirin-containing products while breastfeeding. Aspirin can increase the risk of bleeding in your baby due to its blood-thinning effects. In addition, giving aspirin to children and young adults has been linked to Reye’s syndrome, a rare but serious condition that causes swelling in the liver and brain.

• Take only as much medicine as you need for symptom relief. Also, consider alternative, non-drug therapies, such as putting a cold cloth on your head to relieve a headache.

• Only take medicines for your exact symptoms. Be sure any medicine you take treats your individual symptoms, without ingredients for symptoms you don’t have. This will prevent you from taking more medicine than you need.

• Don’t take extra-strength, long-acting, or sustained-release formulas when possible. These drugs remain in your bloodstream and milk supply much longer than regular-strength drugs. If you need to take a long-acting or sustained-release medication, consult a doctor and then do so after your baby’s last nighttime feed or before his or her longest sleep period.

• Use acetaminophen or ibuprofen for pain relief. While ibuprofen is not recommended during pregnancy, I consider it safe to use when breastfeeding. Why? During pregnancy, ibuprofen is not safe because it can reduce the amount of amniotic fluid in the uterus and can reduce the baby’s blood flow. However, this is not a concern during breastfeeding. I generally prefer that my patients use acetaminophen and ibuprofen over naproxen for pain relief due to the fact that naproxen can stay in your system for longer than these other medications, but it is a good rule of thumb to talk to your doctor or healthcare provider before taking any OTC medicines while breastfeeding.

• Take medicine right after you breastfeed. The highest concentration of the drug is in your bloodstream immediately after taking a medicine. This is called the “peak level.” After that, your body begins breaking down the drug until it is eventually cleared from your system. By taking a medicine right after breastfeeding, it is thought that a smaller amount will pass to the breast milk than if you took the medicine before breastfeeding.

• Look for signs of a reaction in your baby. If your baby is reacting negatively to your medicine, it is often reflected in changes in his or her behavior, such as irritability, hyperactivity, loss of appetite, sleepiness or sedation, skin rash, vomiting, diarrhea, or colic. While these side effects rarely occur, let your doctor or healthcare provider know right away if you notice any difference in your baby’s behavior.

• Use antihistamines and decongestants sparingly. These ingredients may decrease the milk supply. Always use non-drowsy formulas and remember to talk to your doctor before taking any OTC medicines while breastfeeding.

• OTC topical creams are generally safe to use while breastfeeding. The skin absorbs only small amounts of most topical treatments (meaning those you put on your skin), like anti-itch creams and antibacterial ointments, so the amount that will pass into the bloodstream and make its way into the breast milk is even smaller. Just make sure to wash your hands after applying and make sure your baby’s skin doesn’t come into contact with the treated areas.

• Check with your doctor before using certain skincare products. Many ingredients in skin creams and ointments sold over-the-counter at pharmacies today, including the acne treatment benzoyl peroxide and anti-wrinkle and acne-fighting tretinoin (brand name Retin-A), have not been studied during breastfeeding. For this reason, I advise my patients to wait until they are no longer breastfeeding before using these products. However, if you feel as though you must use these products while breastfeeding, it’s best to talk with your dermatologist or pediatrician. They can help you make an informed decision.

• Avoid products that contain caffeine or alcohol. I tell my patients that both alcohol and caffeine are safe to consume while breastfeeding in moderation. However, I generally recommend that my patients avoid both of these ingredients in OTC medicines.

• Don’t take any herbal products without talking to your doctor first. Little is known about their effects on breastfeeding infants. Also, because herbal products aren’t highly-regulated in the U.S., there is no guarantee about the contents of the product.

Remember, always read the Drug Facts label before taking any medication. If you have any questions about whether an OTC medicine is safe to take while breastfeeding, talk to your doctor or healthcare provider.