There are many reasons for red bumps on 2 and a half year old babies, such as hives, eczema, prickly heat, viral rash and other causes. 1. Urticaria: Temporary increase in vascular permeability of the skin mucosa, resulting in limited edema, can cause skin tingling, itching, may lead to 2 and a half year old babies with red bumps on the body. 2. eczema: internal and external stimulation of a variety of factors caused by the skin inflammatory reaction, may lead to skin erythema, rash, itching, etc., can also cause red bumps on the body of 2.5-year-old baby. 3. prickly heat: prickly heat caused by high external temperature and poor perspiration can also cause red bumps on the body of 2 and a half year old babies. 4. Viral rashes: such as measles, rubella, early childhood emergency rash, hand-foot-mouth disease, scarlet fever, etc., can also cause red bumps on the body of 2.5-year-old babies. There may be other reasons for red bumps on 2.5 year old babies, so you need to go to the hospital in time to check and clarify the cause.