A subcutaneous injection is administered as a bolus into the subcutis ,  the layer of skin directly below the dermis and epidermis , collectively referred to as the cutis . Subcutaneous injections are highly effective in administering vaccines and medications such as insulin , morphine , diacetylmorphine and goserelin . Subcutaneous, as opposed to intravenous, injection of recreational drugs is referred to as " skin popping ". Subcutaneous administration may be abbreviated as SC , SQ , sub-cu , sub-Q , SubQ , or subcut. Subcut is the preferred abbreviation for patient safety.