Many breastfeeding problems come down to avoidable mistakes, from what you eat and drink to how your baby latches. Some of these are well known (like limiting alcohol), while others fly under the radar (like a common cold medicine that can slash your milk supply by nearly a quarter). Here’s what to steer clear of and why it matters.
Don’t Take Certain Cold Medications
Pseudoephedrine, the active ingredient in many over-the-counter decongestants, can significantly reduce milk production. A study published in the British Journal of Clinical Pharmacology found that a single 60 mg dose cut 24-hour milk output by 24%, dropping average daily volume from about 784 ml to 623 ml. That’s a meaningful loss from just one pill. If you’re congested, a saline nasal spray or a topical nasal decongestant is a safer choice that won’t interfere with your supply.
Don’t Smoke or Vape Before Nursing
Nicotine transfers directly into breast milk, with levels peaking about 30 to 60 minutes after you smoke. A study in the journal Pediatrics measured what happened when breastfeeding mothers smoked versus when they abstained: infants slept only 53 minutes in the hours after a feeding with nicotine-containing milk, compared to nearly 85 minutes when their mothers hadn’t smoked. The babies woke sooner and spent less time in both active and quiet sleep, with greater sleep disruption at higher nicotine doses.
Importantly, the infants in that study weren’t in the room during smoking, so the sleep disruption came entirely from nicotine in the milk, not secondhand smoke. If you do smoke, waiting as long as possible before nursing (and never smoking in the same room as your baby) reduces both milk-borne and airborne exposure.
Don’t Drink Alcohol Without Timing It
Alcohol moves freely between your blood and your breast milk, so your milk’s alcohol concentration roughly mirrors your blood alcohol level at any given moment. The standard guideline is to wait about two hours per standard drink before nursing. After moderate drinking (one or two drinks), you can generally return to breastfeeding once you feel neurologically normal, meaning you’re no longer feeling any effects. There’s no need to “pump and dump” to clear the alcohol. As your blood alcohol drops, the alcohol in your milk drops with it.
Don’t Overdo Caffeine
The CDC recommends keeping caffeine at or below 300 milligrams per day while breastfeeding, roughly two to three cups of coffee. At that level, most babies are unaffected. At very high intakes (around ten cups a day), infants have shown irritability, jitteriness, fussiness, and poor sleep. If your baby seems unusually restless and you’re a heavy coffee or energy drink consumer, cutting back is worth trying before looking for other causes.
Don’t Eat High-Mercury Fish
Fish is genuinely beneficial during breastfeeding, and the FDA recommends eating 8 to 12 ounces per week of lower-mercury varieties (a serving is 4 ounces). The species to avoid entirely are the ones with the highest mercury levels: king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna. Mercury that enters your bloodstream does pass into breast milk, and infants are especially vulnerable to its effects on the developing nervous system. Salmon, shrimp, tilapia, cod, and canned light tuna are all lower-mercury options.
Don’t Use Cannabis
THC is fat-soluble, meaning it accumulates in breast milk and lingers far longer than most people expect. Studies have detected THC in breast milk anywhere from 6 days to more than 6 weeks after use, with an average elimination half-life of about 17 days. That means even occasional use creates prolonged exposure for your baby.
Research has found that daily or near-daily cannabis use during breastfeeding was associated with slightly reduced motor development in infants at one year of age, in a dose-dependent pattern. While occasional use didn’t produce measurable effects in older studies, those studies were conducted when cannabis potency was much lower than it is today. There is no established “safe” amount.
Don’t Use Retinoid Skincare Products
Vitamin A derivatives, commonly found in anti-aging serums and prescription acne treatments, are associated with retinoid toxicity in infants and should be avoided during breastfeeding. This includes products containing retinol, retinaldehyde, and prescription-strength tretinoin taken orally. If you’re looking to treat acne while nursing, azelaic acid and topical tretinoin (applied away from the breast) are considered safer alternatives. Salicylic acid and mild topical steroids are also generally fine, but keep them off the nipple area where your baby’s mouth makes direct contact.
Don’t Crash Diet
Your body needs additional calories to produce breast milk, roughly 300 to 500 extra calories per day compared to your pre-pregnancy needs. Severely restricting food intake or attempting rapid weight loss can reduce your milk supply. Gradual, moderate weight loss of about one to two pounds per week is unlikely to affect production, but crash diets, juice cleanses, and extreme calorie cutting can. Steady, balanced eating keeps your supply more stable than any supplement or lactation cookie.
Don’t Ignore Latch Problems
A poor latch is one of the most common and fixable breastfeeding mistakes, but many parents assume the pain is just normal. Signs that your baby isn’t latched correctly include: their mouth is barely open, their lips cover only the nipple rather than a good portion of the areola, their chin doesn’t rest against your breast, and you feel sharp or pinching pain. A proper latch should feel like a deep tugging sensation, not a pinch.
Pain that persists beyond the first few seconds of a feeding, cracked or bleeding nipples, and a baby who seems frustrated or hungry shortly after nursing are all signals worth addressing. A lactation consultant can often fix latch issues in a single visit, and early correction prevents weeks of unnecessary pain and low milk transfer.
Don’t Overuse Certain Herbs
Sage, peppermint, and parsley are sometimes deliberately used to reduce milk supply during weaning, which tells you something about their potency. In normal cooking quantities, these herbs are fine. But drinking concentrated sage tea (made with 1 to 3 grams of dried sage leaves), consuming large amounts of fresh parsley, or using peppermint oil can noticeably suppress lactation. If you’re struggling with low supply, check whether any herbal teas or supplements you’re taking contain these ingredients.