The easiest way to use くすぐったい and かゆい
I’d say くすぐったい and かゆい are a little bit confusing, however, their nuance is different from each other and the rule of using these words is not so difficult to use, so let’s try to master here.
When feeling tickle, you could use くすぐったい. For example, your friends tickle you, your dog licks your sole and etc. Unlike かゆい, when someone stops tickling you, it would be gone. And some people use こしょばい or こそばい as the meaning of くすぐったい. They are the same meaning.
When insects, mosquito and so on bite someone, he/she is going to be itchy which is かゆい. Unlike こしょばい, when someone feels かゆい, he/she may scratch his/her body. And かゆい is one of the bad signals or symptoms of your body such as allergy.