It is uncommon, but possible, to have a true allergic reaction to rice cereal.
Symptoms of an allergic reaction might include:
- Blood in the stools
If one of these is happening, or you feel strongly that your baby is having an allergic reaction for another reason, talk to your doctor. You can discuss the best next steps. Your doctor may want to do some tests or might recommend other foods.
Constipation is very common with rice cereal. (I mention this in case you thought this might be an allergic reaction.) If your baby is constipated, you might want to try oatmeal. Giving your baby pureed vegetables and fruit (especially prunes) may help. And giving your baby some water every day can useful, too.
Your doctor is your best resource for this question, as he or she knows about your baby's health and growth.