Chafing thighs, a k a Chub Rub

Blisters and rashes on women’s inner thighs occur when unprotected skin rub against other skin or loose fitting clothes. The severity of the friction depends on factors like pressure, skin characteristics and environmental factors. Moist conditions caused by weather or sweating and characteristics of clothes worn will thus accentuate the problem. 
Overweight or athletic women with large muscle mass are most likely to experience thighs chafing but it is in reality a very common problem for women of average weight and constitution.