First things first, use only open or free-flow cups when giving your little one a drink to protect their teeth.
In terms of what should go into that cup, from 6-12 months only water and breast milk or infant formula should be offered with or between meals. Other options, such as fizzy drinks, flavoured milks, fruit juices and smoothies, have a high sugar content and risk causing tooth decay.
It’s important to note that ‘Follow-on’ formula is not necessary if you’re weaning well, as the nutrients that it is fortified with your baby will now be getting from solid foods. If you are using infant formula rather than breastmilk it might be that you need to supplement this with water in hotter months (breastmilk will adapt to ensure the water content is sufficient).
Whilst only breast milk, infant formula or water are appropriate drinks, full fat cow’s, goat’s or sheep’s milk can be used in cooking. It is just advised that milk alternatives – soya, almond, oat, coconut etc. – are avoided until 1 year unless you’re advised to use plant-based alternatives by a healthcare professional eg. if your little one has cow’s milk protein allergy.
At 1-year, when your baby should be getting the majority of their nutritional needs from food, whole cow’s milk can be introduced as a drink and/or breastmilk continued. Unsweetened, fortified milk alternatives can also be offered as drinks now and infant formula is no longer necessary. However, rice milk is an exception to the other plant-based milks and should not be introduced until age 5.