The doctor says my baby has scabies; how can I help her stop itching?

Zyrtec/Claritin. The itching is due to an allergic reaction to the infection and can last several days to weeks. A nonsedating antihistamine line zyrtec or Claritin (loratadine) is probably the best option.
Aveeno bath,benadryl (diphenhydramine) Your baby might find comfort with aveeno oatmeal bath powder mixed with bath water, which is very soothing to itchy skin. Try not to make the water too hot as very warm water could intensify the itching. Depending on the age of your child, children's Benadryl (diphenhydramine) may help itching and improve sleep (talk to your doctor first). Also, Benadryl (diphenhydramine) itch relief spray might provide temporary relief as well.