Bottles, teats etc. must be sterilized. You can purchase sterilizing units, but if these aren’t available as when you are visiting relatives, you can sterilize a bottle in any plastic tank with the appropriate chemicals.
Bottle feeding babies with formula will bring about some changes.
Their stools will change in color and be firmer, much more like an adult stool. There is an increased chance of constipation and of colic. Here's a resource you can consult if that happens.
Breast milk is complex – it changes during a feed from the thin fore milk which gives baby a refreshing drink, to the much richer hind milk, full of nutrition. This just isn’t possible with formula.
Eventually of course baby will want something more than either breast milk or formula though these should be continued alongside weaning food.
