Hi, In Dengue fever up and down of platelets are fine it's because of the viral infection in body. When the load of virus will decrease the platelet counts will increase automatically. Just take care that you drink lots of water and don't take pain killers only paracetamol for fever. Platelets will increase once fever start coming down. You just follow up with doctor and you don't need admission unless he start having pain in abdomen, vomiting, breathing problem and irritable. Hope this might be helpful to you.