What measures can a client take to relieve itching under a plaster cast?

Using a hair dryer on a low setting is an effective measure for relieving itching under a plaster cast. The warm air can help to soothe the skin underneath the cast, providing comfort by reducing the sensation of itching. It's important for the hair dryer to be set on low to prevent discomfort or overheating the skin, as direct heat can cause burns or further irritation.

Other methods, such as applying ice or trying to remove the cast, are not advisable. Ice can create moisture within the cast and may worsen the problem or lead to skin issues. Removing the cast is not an option, as it must remain in place to properly support and heal the injured area. Antihistamines might alleviate itching caused by allergic reactions, but they don't address itching specifically related to the constriction of skin under a cast. Therefore, using a hair dryer on low is the most suitable method for providing relief while still maintaining the integrity of the cast and the healing process.