A child's first tooth usually appears by 6 months of age, and a complete set of 20 primary or first teeth Teeth Physical growth refers to an increase in body size (length or height and weight) and in the size of organs. From birth to about age 1 or 2 years, children grow rapidly. After this rapid infant... read more usually develops by 2½ years.
Before a tooth appears, the child may cry, be fussy, and sleep and eat poorly. The child may drool, have red and tender gums, and chew constantly on objects like toys and crib rails during tooth eruption.
Teething does not cause fever Fever in Infants and Children Normal body temperature varies from person to person and throughout the day (it is typically highest in the afternoon). Normal body temperature is higher in preschool-aged children and highest... read more 
(temperature of 100.4° F or 38° C or higher). Children who have fever and who are especially fussy should be evaluated by a doctor for an infection because these symptoms are not caused by teething.
Teething infants get some relief from chewing on hard objects (such as teething biscuits) or cold objects (such as firm rubber or gel-containing teething rings). Massaging the child's gums with or without ice also may help. If a child is extremely uncomfortable, weight-based doses of acetaminophen or ibuprofen are usually helpful.
Teething gels are not recommended because they are not any more effective than other measures of pain relief, and some contain a potentially dangerous substance called benzocaine. Benzocaine can rarely cause a serious condition called methemoglobinemia, which affects the ability of the blood to carry oxygen.
