Do I need to sterilize bottles and for how long?

What the evidence says

Cleaning (washing with hot soapy water) is different from sterilizing (killing all germs), and both matter. Health Canada advises thoroughly washing bottles, nipples and caps, then sterilizing by boiling them in an open pot for about two minutes before letting them air dry. Other guidelines, like the NHS, recommend boiling for at least 10 minutes, and the CDC recommends 5 minutes, so times vary somewhat by source, and you can also check your bottle manufacturer's instructions.

Most guidelines agree bottles should be cleaned after every single feed, and sterilizing daily is especially important if your baby is younger than 2 months old, was born prematurely, or has a weak immune system. For older, healthy babies, thorough cleaning after each use may be enough, and daily sterilizing may not be strictly necessary, though many guidelines still suggest continuing to sterilize equipment until your baby turns 12 months old.

Besides boiling, you can also sterilize with a cold-water chemical/bleach-based solution (leaving items submerged for the manufacturer's recommended time, often around 30 minutes) or with a steam or microwave steriliser. Whichever method you choose, items must be cleaned first, since sterilizing does not remove dirt or milk residue.

If you use a dishwasher with a hot water and heated drying (or sanitizing) cycle, a separate sterilizing step usually isn't needed for daily use, according to the CDC.