Colic usually starts when a baby is a few weeks old and stops when they're 4 or 5 months old.¹ No one knows what causes it.

Some researchers think that colic could be caused by gas or painful bowel cramps. Some babies might be sensitive to lactose, a sugar that's in cow's milk. Other babies may be sensitive to the protein in cow's milk.¹ So your baby might get colic if you are giving them formula milk that's based on cow’s milk.

Colic can be distressing, but it doesn't mean your baby is ill.

But other researchers think that colic isn't caused by stomach problems. They think that some babies just cry a lot, and some parents are more worried by their baby's crying.

There are things that seem to trigger colic, although researchers don't know for sure. ^{2 3}

If you're breastfeeding the following things could cause your baby to have colic.

• What you eat. If you're breastfeeding, what you eat goes into your breast milk. Chocolate, dairy products, spicy food, caffeine (found in coffee, tea, cola and some other drinks) and some fruits and vegetables may bother your baby and bring on colic.
• A medication that you might be taking. This is because some medications go through to your breast milk.
• Smoking. If you smoke, your baby will get nicotine and other chemicals through your breast milk.

Fast bottle-feeding may also trigger colic. If you're bottle feeding and your baby feeds in less than 20 minutes, the hole in the bottle's nipple might be too large.

It's important to remember that colic isn't caused by you doing anything wrong. And it won't harm your baby.