If a woman ingests hydantoins, barbiturates, or carbamazepine, her breastmilk will contain significant quantities of these substances. No back-up is needed. There is no evidence that antimalarial medications reduce the effectiveness of oral contraceptives. Chloroquine and related antimalarials are excreted in breast milk. Chloroquine, primaquine, and tetracycline have not shown any effect on oral contraceptive hormonal levels and are not known to reduce the effectiveness of POPs.
Children are especially sensitive to chloroquine and primaquine.
No back-up is needed. However, if a breastfeeding woman has resumed menstruating and is beginning the pills later than the first 7 days of her cycle, some programs recommend that she use a back-up method for 7 days after beginning POPs. The cervical mucus thickens enough to prevent sperm penetration within 24 hours. Also, the synergistic protection against pregnancy conferred by concurrent POP use and breastfeeding should sufficiently eliminate a client's risk of conception. If the breastfeeding woman is still amenorrheic, missed pills are of minimal consequence.