Rashes over body of children may of different types and due to different reasons.Most common rashes over the body of children are due to allergy.Allergy may be due to any thing which is in the air or which the child commonly eats or drinks.Allergic rashes may cover the whole body within minutes or progresses over the day.Some children may have some congenital defect and they are more vulnerable to allergic rashes.Allergic rashes are usually red coloured and wheel shaped but it can be like pin heads and confluent erythmatous rashes.Sometimes there may be swelling of lips ,tongue and digits.In the most severe form,there is swelling of the larynx(the door to the lungs) causing laryngeal edema and there is spasm (narrowing) of bronchi(airway).In this case life of the child may be endangered.So,any rash over the body of child should not be ignored and a doctor should be consulted as soon as possible.Allergy may be caused by any drug,whether the child has taken it previously or not.Allergy may be due to any vaccine.
Rashes may be due to viral infections in the form of Measles,Rubella,or Chicken Pox.These can be identified only by a qualified doctor.Vaciines are available to prevent these viral diseases..
Rashes over body may be due to some autoimmune diseases which is chronic condition requiring detailed investigations and complex treatment.
Rashes may be due to atopic dermatitis which requires long term treatment..
Rashes may be due to scabies in which case other family members are also affected.