I, truthfully, contemplated serving peanut butter for the first time to my oldest in the ER parking lot, just in case something happened. If you are concerned your baby could be at risk for a peanut allergy, feed it to them at their pediatrician's office.  The following are signs of an allergic reaction: Swelling of the face, puffy eyes Redness around their mouth Hives Digestive problems Runny nose  More serious signs include trouble breathing, throat swelling, and swelling in and around the mouth. Most allergic reactions will happen immediately after eating peanut butter; however, there can be a delay of symptoms for a few hours. Therefore, it's recommended not to feed your baby peanut butter within a short time frame of bedtime. Finally, if your baby suffers from eczema or an egg allergy, they are more likely to have a peanut allergy. If your baby falls into that category, an allergist can perform a skin test to check for any evidence of a peanut allergy before offering peanut butter for the first time.