Breastfeeding and Maternal Medication
Most drugs appear in the milk, but only in very tiny amounts. Although a very few drugs may still cause problems for infants even in tiny doses, this is not the case for the vast majority. Mothers who are told they must stop breastfeeding because of a certain drug should ask to be prescribed an alternative medication which is acceptable for breastfeeding mothers. In this day and age, it is rarely a problem to find such an alternative. If the prescribing physician does not know how to proceed, s/he should get more information. If the prescribing physician is not flexible, the mother should seek another opinion.

Most drugs may be considered safe for the mother to take and continue breastfeeding if:

Medications applied to the skin, inhaled or applied to the eyes or nose are almost always safe for breastfeeding.

You can still breastfeeding after general, regional or local anaesthesia. As soon as you are up to it. Medications you might take afterwards for pain are almost always permitted. Immunizations given to the mother do not require her to stop breastfeeding (including with live viruses such as german measles, Hepatitis A and B).

Get reliable information before stopping breastfeeding. Once you have stopped it may be very difficult to restart, especially if the baby is very young.

Breastfeeding and Maternal Illness
Very few maternal illnesses require the mother to stop breastfeeding. This is particularly true of infections. Most infections are caused by viruses. Most infections caused by viruses are most infectious before the mother realizes she is sick. By the time the mother has fever (or cold, runny nose, diarrhea, vomiting, rash etc), she has already passed on the infection to the baby. However, breastfeeding protects the baby against infection, and the mother should thus continue breastfeeding, in order to protect the baby. If the baby does get sick, he usually is less sick than if breastfeeding had stopped. But often mothers are pleasantly surprised that their babies do not get sick at all. The baby was protected by his mother's continuing breastfeeding.

The only exception to the above is HIV infection in the mother. Until we have more information, it is considered safer for the baby that the mother who is HIV positive not breastfeed, at least where the risks of bottle feeding are acceptable. There are situations, however, even in Canada, where the risk of not breastfeeding is elevated enough that the mother who is HIV positive should nevertheless breastfeed her baby. The final word is not in, however.

Most other maternal illnesses raise questions because of the drugs the mother might have to take. These should rarely be a problem (see above).

X-rays and scans: Ordinary X-rays do not require a mother to stop breastfeeding even when used with contrast (e.g. IVP). A CT scan, MRI scan, even when used with contrast do not require a mother to stop. A radioactive scan (e.g. lung scan, bone scan) does not require a mother to stop. The only exception is a thyroid scan. However, most of the time the scan does not have to be done. See below.

A not uncommon problem in the early months after delivery is a condition called postpartum thyroiditis, a temporary derangement in the thyroid gland's function. A useful test to help understand the condition is a thyroid scan. However, the test requires that radioactive iodine be given to the mother and this material must not be given to nursing mothers. The radioactive iodine will be found in the milk for weeks, and concentrated in the baby's thyroid. There are ways of dealing with postpartum thyroiditis without doing this test. The drugs a mother might have to take to treat postpartum thyroiditis are compatible with continued breastfeeding (e.g. propranolol, propylthiouracil)

Breast Problems
Mastitis (breast infection) and breast abscess are not reasons to stop breastfeeding. Although surgery on a lactating breast is more difficult, the surgery does not necessarily become easier if the mother stops breastfeeding, as milk continues to be formed for weeks after stopping breastfeeding.

Mammograms are more difficult to read if the mother is breastfeeding, but can still be useful. Once again, how long must a mother wait for her breast no longer to be considered lactating? Evaluation of a lump can be done by other means besides mammography. Discuss options with your doctor. Let him/her know breastfeeding is important to you. A needle biopsy, for example, can be done of a lump which is of concern.

New Pregnancy
There is no reason that you cannot continue breastfeeding if you become pregnant. There is no evidence that this does any harm to you, to the baby in your womb or to the one who is nursing. If you wish to stop breastfeeding, take your time and wean slowly.

Infant Problems
Breastfeeding rarely needs to be discontinued for infant illness. Through breastfeeding, the mother is able to comfort the sick child, and, at the same time, the child is able to comfort the mother.