The best prevention is to avoid any known allergens as well as the substances that commonly cause serious allergic reactions.
If your baby is allergic to certain foods, it will take only a trace amount to trigger a reaction, so it's important to read labels carefully and ask at restaurants or friends' houses whether a meal contains any of the off-limit items. You'll need to be vigilant about this for your child until he can do it for himself. For more tips, check out the Food Allergy Network.
If insect bites or stings cause trouble, help your baby find places to play that are free of bugs. Don't rely on bug sprays — they don't repel bees and fire ants, which commonly sting children.
In addition, once your baby can walk, don't let him toddle around outside barefoot. Many children are stung when they unintentionally step on a stinging or biting insect.
If your child has had a severe allergic reaction, his doctor may recommend that when he gets a little older you carry an EpiPen Jr., a penlike injection device loaded with epinephrine. It's designed for children weight 33 to 66 pounds (15 to 30 kilograms) and is available by prescription only.
Also make sure anyone who ever cares for your baby — caregivers, daycare workers, relatives — knows about your child's allergies and exactly what to do if he has a reaction.
Finally, once your baby has had a severe reaction such as anaphylaxis, it's important for him to wear a medical-alert ID bracelet (available in most pharmacies). This will alert healthcare providers to his condition in case of an emergency.