Most mothers choose to breastfeed because they want the best food for their baby. But as the number of breastfeeding mothers continues to rise once again, so does the use of drugs - both legal and recreational

Over the years, far too many women have been wrongly told that they had to stop breastfeeding because of various drugs or medications they may be taking.

Some doctors are hesitant to prescribe any medications for a mother who is breastfeeding, once they learn that even a tiny amount will enter the mother's milk.

Many doctors are also afraid to prescribe a drug because of the conservative approach taken towards giving drugs to pregnant women; they feel that if a drug could possibly cause birth defects in a pregnant woman, they shouldn't give it to a lactating woman.

Doctors tend to err on the side of caution rather than undertake research in order to reassure the mother that the medication is safe for her baby.

The safe side

Many references will recommend that no drug should be taken by a breastfeeding mother unless it has been proven absolutely safe in all circumstances. The problem with that is that there is virtually no drug that can be said to be absolutely safe all the time.

Most medications have not been tested in nursing mothers, so no one knows exactly how a given drug will affect a breastfed baby. Since very few problems have actually been reported, however, most over-the-counter and prescription drugs are considered safe in most situations.

One frequently asked question is why is it safe for a pregnant woman to take a particular medication when it may not be safe for a breastfeeding mother?

In a pregnant woman, the mother's system takes care of breaking down and eliminating drugs, whereas in the breastfed infant it is the infant who must break down and eliminate the drug from the breast milk.

Three known facts

You should be aware that there are three things we know for sure about drugs and breast milk:

1. Nearly all drugs pass into human milk but dilution in the mother's body before this entry, and the relatively small volume of milk swallowed, will mean that whatever drug reaches the baby is insufficient to cause adverse effects.
2. Almost all medications appear in very tiny amounts - usually less than one per cent of the maternal dose - and the majority of drugs are safe for the baby.
3. Very few drugs are contraindicated for breastfeeding mothers and although there are a few drugs that may still cause problems for infants, even in tiny doses, this is not the case for the vast majority.

Key factors

The decision about continuing breastfeeding when the mother takes a drug is far more involved than whether the baby will get any in the milk - and the issue of which drugs are safe to take during lactation is quite complicated.

Many factors have to be taken into consideration, such as:

• The route of administration: drugs can enter your system in several different ways. Orally (by being swallowed), intravenously (injected directly into the blood stream), intramuscularly (being injected into the muscles), topically (from creams applied to the skin), or through inhalation (having been breathed in). Medications taken topically or from inhalation reach the milk in lesser amounts and more slowly than other routes and are almost always safe. Oral medications take longer to get into the milk - because they have to go through the mother's metabolic processes before they enter her blood stream and then the milk supply - than intravenous or intramuscular routes.
• The amount taken: the higher the dosage, the more the drug transfers into the milk.
• How often the drug is taken: medications/drugs taken 30-60 minutes before breastfeeding are likely to be at peak levels when your baby feeds.
• Your baby's age and level of maturity: premature babies have immature organs, and may, therefore, have trouble processing and eliminating even small quantities of drugs that might not cause problems for larger, full-term babies. However, even a full-term baby's protective metabolic system is not fully developed for the first few weeks of life, so may not be able to handle chemicals in milk as well as a baby who is several months old.
• The frequency and volume of feeding: the baby who is feeding once or twice a day and is supplemented the rest of the time will obviously receive less of a drug than the baby who is totally breastfed and who may be feeding ten to 12 times a day.
• Duration of drug therapy: a medication taken for weeks or months may have a greater impact on breastfeeding than one taken for just a few days.
• Type of medication: the characteristics of the drug, including the elimination time (just how quickly the body's metabolism can remove the drug), the fat solubility (a property that governs just how easily a drug can enter the breast milk and the most important parameter that determines drug penetration into breast milk) and half-life (an indication of the length of time a drug remains within the body) all affect how much of the drug is transferred into the breast milk.

General rules

There are some general guidelines for taking drugs while breastfeeding: