Food
You ate what the doctor ordered for nine months, and now you're dying for a big bowl of chili with all the fixings. While there's no reason not to indulge the occasional craving, you might want to hold off on the spicy food (and onions and cheese) until you're sure your nursing baby isn't sensitive to what you're eating. Gas and fussiness in your baby are the most common signs that something you ate has made its way into your breast milk. Diarrhea and a skin rash could signal an allergy. Talk to your doctor before making any changes to your diet — good nutrition is essential for nursing mothers.

Food	Solution
Cabbage, onion, garlic, broccoli, Brussels sprouts, cauliflower, peppers, cucumbers, and turnips can cause gas and fussiness, which usually lasts up to 24 hours and then disappears.	Cut out the offending foods in your diet (at least for the first few months of breastfeeding) until your baby's gastrointestinal tract is more developed.
Cows' milk products (such as milk, cheese, yogurt, and even butter) in your diet may cause an allergic reaction in your baby. Symptoms can appear anywhere from a few minutes to a few hours after breastfeeding and may include diarrhea, rash, fussiness, and gas or runny nose, cough, or congestion.	Cut out all dairy products from your diet for two weeks to see if your baby's condition improves.
Citrus fruits such as oranges, lemons, limes, grapefruits, and tangerines are common irritants. Symptoms may include fussiness, vomiting, diarrhea, skin rashes, hives, and sniffles.	Cut out the suspect foods for about a week (long enough to get them completely out of your system). Then reintroduce one food at a time to find the culprit.
Chocolate contains a chemical called theobromine that's a gastric irritant. Symptoms may include fussiness and diarrhea.	Cut out the candy bars for about a week (long enough to get them completely out of your system) to see if your baby's condition improves.
Eggs, wheat, corn, fish, peanuts, nuts, and soy are allergens. Symptoms may include fussiness, vomiting, diarrhea, skin rashes, hives, and sniffles. "Stray" proteins from some of these foods may be absorbed into your bloodstream and pass into your milk.	Keep a chart of what you've been eating, and when. Cut out the suspect foods for about a week (long enough to get them completely out of your system). Then reintroduce one food at a time to find the culprit. But don't drastically alter your diet without talking to your doctor first.

Herbs
Although herbs are considered natural alternatives to certain drugs, they can be just as powerful — and just as toxic. Like drugs, chemical ingredients from herbs do get into breast milk. While herbs such as fenugreek and fennel have been used for centuries to increase a nursing mother's milk supply, little is known about how herbs affect a nursing baby. Play it safe and consult with your doctor before taking any herbal remedy.

Herbs	What you should know
Chamomile, ginger, echinacea	Taken in teas, these herbs probably pose no danger to your baby. Drink any herbal tea with caution, however, especially when you don't know all the ingredients. (Stay away from goldenseal, which often comes with echinacea, because it can be toxic in moderate doses and experts aren't sure of its effects on nursing babies.) Most teas are benign, but some have been known to cause liver toxicity, warns Jan Barger, a registered nurse and lactation expert.
Ground fenugreek, anise, borage, raspberry leaves, blessed thistle, saw palmetto, dill, chaste tree, garlic, nettles, fennel seeds, goat's rue, false unicorn root, vervain, cinnamon	These herbs are often used as milk boosters and are generally safe for your baby. Fenugreek is sometimes sold in Mother's Milk tea, which can contain other herbs that may not be good for your baby. Taking any of these herbs in high dosages may cause your perspiration to smell like maple syrup.
Mint, sage, parsley	These herbs, most often eaten in food, may dry up your milk supply. Avoid them if you're trying to breastfeed, but you can use them when you start to wean — they won't hurt your baby.
Feverfew	This herb is used to treat migraines. Don't take it while breastfeeding, as it may increase your baby's heart rate.
St. John's Wort	This herb is used to treat depression. Don't take it while breastfeeding as no studies have been done to see whether it's safe for nursing moms. It could affect milk production and can reduce the effectiveness of certain drugs.

Alcohol, Caffeine, and Nicotine
It's just as important to safeguard your baby from the ill effects of alcohol, nicotine, and caffeine while breastfeeding as it was when you were pregnant.

Substance	What it does	What you can do
Alcohol	Although alcohol passes through your milk, the amount your baby gets is much less than the amount you drink. Studies have shown that alcohol levels in breast milk peak about 30 to 90 minutes after one drink,	It's probably fine to have one or two glasses of beer or wine a week. If you want to indulge and are concerned about alcohol passing to your baby, wait until the last feeding of the day — just after you nurse rather than just before — to allow a couple of hours per drink for the alcohol to metabolize.
Caffeine	Your baby may be more irritable and feed more frequently if you ingest a lot of caffeine. Babies can't get rid of caffeine efficiently, so it can build up in their systems. Remember, caffeine can be found in chocolate, soft drinks, and some herbal teas and medications, in addition to coffee and tea. Too much caffeine can also cause sleep problems and nervousness.	One or two cups of coffee a day won't harm your baby, but try to avoid caffeine or at least reduce your intake while you're breastfeeding. Try drinking decaffeinated coffee and tea, and avoid colas and other carbonated drinks that have added caffeine.
Nicotine	Nicotine ingested by smoking tobacco can get into breast milk. Heavy smoking (more than a pack a day) has been known to decrease milk production and to cause vomiting, diarrhea, rapid heart rate, and restlessness in babies. In general, though, nicotine is not easily absorbed into a baby's intestinal tract and is quickly metabolized. Babies of smokers, breastfed or not, are prone to colic and respiratory infections and smoking can increase the risk of SIDS in newborns (but breastfed babies of smokers are still healthier than their formula-fed peers).	Stop smoking, for your sake and your baby's. But if you just can't quit while you're nursing, try cutting back on the number of cigarettes you smoke each day, and don't smoke just before breastfeeding or around your baby, especially indoors.