Yes, Benadryl is used in guinea pigs to help with itching. The dose is based on weight--consult with your veterinarian to determine an appropriate dose. Guinea pigs should be weight on a gram scale.
Benadryl does not treat the underlying cause of the itching so it will likely return until the reason for the itching is found and treated.
Benadryl does not treat the underlying cause of the itching so it will likely return until the reason for the itching is found and treated.