Drug	Reported signs or symptoms
Alcohol (ethanol)	With large amounts, drowsiness, diaphoresis, deep sleep, weakness, decrease in linear growth, abnormal weight gain; maternal ingestion of 1 g per kg daily decreases milk ejection reflex
Aspirin (salicylates)†	Metabolic acidosis (one case)
Atenolol†	Cyanosis; bradycardia
Barbiturate	Should be given with caution; blood concentration in the infant may be of clinical importance
Bendroflumethiazide	Suppresses lactation
Bromide	Rash, weakness, absence of cry with maternal intake of 5.4 g per day
Caffeine	Irritability, poor sleeping pattern, excreted slowly; no effect with moderate intake of caffeinated beverages (2 to 3 cups per day)
Carbimazole	Goiter
Chloral hydrate	Sleepiness
Chlorthalidone	Excreted slowly
Cisplatin	Not found in milk
Contraceptive pill with estrogen/ progesterone	Rare breast enlargement; decrease in milk production and protein content (not confirmed in several studies)
D (vitamin)	Follow up infant's serum calcium level if mother receives pharmacologic doses
Danthron	Increased bowel activity
Dapsone	Sulfonamide detected in infant's urine
Dexbrompheniramine maleate with d-isoephedrine	Crying, poor sleeping patterns, irritability
Estradiol	Withdrawal, vaginal bleeding
Ethosuximide	Drug appears in infant serum
Fleroxacin	One 400-mg dose given to nursing mothers; infants not given breast milk for 48 hours
Indomethacin	Seizure (one case)
Iodides	May affect thyroid activity; see iodine
Iodine	Goiter
Iodine (povidone-iodine, e.g., in a vaginal douche)	Elevated iodine levels in breast milk, odor of iodine on infant's skin
Isoniazid	Acetyl (hepatotoxic) metabolite secreted but no hepatotoxicity reported in infants
Lithium†	One third to one half therapeutic blood concentration in infants
Methyprylon	Drowsiness
Morphine	Infant may have measurable blood concentration
Nalidixic acid	Hemolysis in infant with glucose-6-phosphate dehydrogenase (G6PD) deficiency
Nitrofurantoin	Hemolysis in infant with G6PD deficiency
Phenobarbital†	Sedation; infantile spasms after weaning from milk containing phenobarbital, methemoglobinemia (one case)
Phenytoin	Methemoglobinemia (one case)
Sulfapyridine	Caution in infant with jaundice or G6PD deficiency and ill, stressed, or premature infant
Sulfisoxazole	Caution in infant with jaundice or G6PD deficiency and ill, stressed, or premature infant
Tetracycline	Negligible absorption by infant
Theophylline	Irritability
Thiouracil	Drug not used in the United States
Tolbutamide	Possible jaundice