My 18 month old is running 99.7 degree fever. Should I take him to doctor?

Depend. Depend if your baby have any other symptoms such as running nose , congestion, cough etc..., how long has it been with fever, does pt respond with tylenol (acetaminophen) or advil liquid or not.If low grade fever <100 more than 3 days i would take the baby to be seen by a doctor.If fever stays persistent and fever gets higher, you need to take baby to be seen sooner.