The importance of a pharmacist’s consultation for lactating mothers

The rate of breastfeeding has reached over 75% in the U.S. The goal set by Healthy People 2020 is 82%. The Surgeon General has released a “call to action” that promotes breastfeeding for every mother who wishes to do so.

The benefits of breastfeeding extend to both mother and infant. Studies have shown that lactation improves glucose metabolism and insulin sensitivity, thereby reducing the risk of type 2 diabetes. Cumulative lactation of longer than one year is associated with a 28% decrease in both breast and ovarian cancers. The overall effect of breastfeeding also helps mobilize fat, which stimulates a quicker return to the mother’s pre-pregnancy weight.

Up to 99% of breastfeeding mothers take medications. As pharmacists, we need to provide these women with guidance about the safe use of medications.

Drug effects during lactation

Most medications are compatible with breastfeeding; however, a small proportion are contraindicated for nursing mothers and pose harm to their infants. Drug concentrations are highest in breast milk within the first two weeks postpartum as the mother’s physiological system reverts to a non-pregnant state. Adverse drug events via lactation are most common in infants younger than two months and rare in those older than six months.

Some medications can reduce milk production. Estrogen-containing contraceptives should be resumed about six weeks after delivery when the supply of breast milk is well-established, or they can be replaced with progestin-only products that are unlikely to affect milk supply. Cold and allergy remedies such as antihistamines and decongestants also have a “drying effect” on breast milk. Alternatives such as steroidal nasal sprays can be considered instead.

Analgesics

OTC analgesics ibuprofen and naproxen for mild to moderate pain are compatible with breastfeeding because minimal amounts are excreted in human milk. Acetaminophen is also considered safe, as is low-dose aspirin. High-dose aspirin, however, may contribute to rash, platelet abnormalities, and Reye syndrome. Codeine should be avoided because it can result in dangerously high levels of morphine, the active metabolite, in infants and cause over-sedation. Nursing mothers should also avoid oxycodone because central nervous system depression has been noted in 20% of breastfed infants.

Antibiotics

Antibiotic levels in breast milk are generally minimal. The most common adverse effects for the infant are diarrhea and colic. Sulfonamides should be avoided during the last trimester of pregnancy and within the first month of delivery because of the risk of jaundice. Advise nursing mothers who take a single high dose of metronidazole to discontinue breastfeeding for 12 hours to allow excretion of the drug.

Antihypertensives and antidiabetics

Beta-blockers such as atenolol should be avoided because of possible cyanosis and hypothermia; propranolol could cause bradycardia and hypoglycemia. Other antihypertensives such as lisinopril and nifedipine are considered safe during breastfeeding.

Antidiabetics such as metformin and insulin are compatible with breastfeeding. Very low concentrations of metformin are detectable in breast milk. Although insulin is excreted into breast milk, as a polypeptide hormone it is digested in the infant’s GI system and thus poses no risk.

Herbal and dietary supplements

Herbal products and dietary supplements should be used carefully because reliable data on the safety of these products are limited. Yohimbe has been associated with fatalities, while St. John’s wort causes colic and lethargy in breastfed infants. Iron and vitamin supplements commonly used by nursing mothers are considered safe at recommended daily amounts.

For more information

The pharmacist’s consultation is imperative to the nursing mother for weighing the benefits and risks of medications. Nursing mothers may also consult LactMed (https://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm) for information on medications.

Janet Chang is a PPSI intern and 2017 PharmD candidate at Touro University, Vallejo, Calif. She would like to thank Aglaia Panos, PharmD, for her assistance in the preparation of this article. Contact her at janet.chang@tu.edu.