A wheal occurs on the skin from which of the following injections?

A wheal, which is a raised, itchy area of skin that often indicates an allergic reaction or a local immune response, occurs specifically as a result of intradermal injections. In an intradermal injection, the medication is administered into the dermis, the layer of skin just beneath the outer epidermis. This technique creates a small pocket of fluid and can lead to the formation of a wheal due to the localized swelling that results from the injection.

In contrast, subcutaneous injections deliver medication into the fatty layer just under the skin, where wheal formation is not typical. Intramuscular injections involve administering medication deep into muscle tissue, which also generally does not cause a wheal. Intravenous injections deliver medication directly into the bloodstream and do not result in wheal formation either. The specific nature of how intradermal injections work in relation to skin anatomy is what leads to the characteristic wheal formation following such injections.