system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it bad to scratch itches due to mosquito bites, poison ivy, chicken pox, etc? Is there ever a time when it is good to scratch?
gpt
When you contact poison ivy, there is oil on the leaves that causes the itch. If you scratch at the itch, you spread the oil and prolong the itching. When you get chicken pox, not only can you spread the contact area of the spot, but you can get scars as you constantly scratch skin weakened by the disease. Scratching mosquito bites only deadens the itch for a minute or two and can spread the mosquito saliva that causes the itch. Better to take a benydryl and go to sleep.