Hi, Many viral upper respiratory infections are associated with oral lesions, and need not be worried about. Yes, they are contagious, and others, especially children in the household can get infected. Most of these are benign and will recover in 3-5 days, and no need or use of isolating them (infectivity will start before symptoms) from others. If the fever is not coming down by 3rd day, or if there are painful oral blisters turning into ulcers, kindly review with your doctor to rule out herpes stomatitis, that may need anti-viral treatment. Meanwhile continue paracetamol and give plenty of oral fluids. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Muhammed Aslam T. K., Pediatrician