Subcutaneous Route

The SC (subcutaneous) route is commonly used for the injection of small amounts of medication directly beneath the skin.
This method is particularly advantageous for medications like insulin, which may require regular dosage.
Injections are typically administered in the loose interstitial tissue of the following sites:
- Outer upper arm
- Anterior thigh
- Lower abdomen

Injection Technique:
- When injections are frequently given, such as daily insulin, it is crucial to rotate the injection site to prevent tissue damage and complications such as lipodystrophy.
- The skin at the injection site should be thoroughly cleansed with an alcohol swab or antiseptic solution to minimize the risk of infection.

Dosage and Injection Volume:
- The maximum volume that can be comfortably injected subcutaneously is about 1.3 mL.
  - Injections exceeding 2 mL are likely to cause painful pressure and discomfort.
- Syringes with capacities up to 3 mL are typically used for SC injections.
- The common sizes of needles for these procedures are 24- to 26-gauge, with a cannula length ranging from three-eighths of an inch to an inch.
- For insulin specifically, the needles generally used are 25 to 30 gauge, with lengths of five-sixteenths to five-eighth of an inch.
Precautions:
- If blood appears in the syringe upon insertion, a new injection site should be selected immediately to avoid intravascular injection, which could lead to complications.
- Caution is advised with irritating drugs or those in thick suspension formulations, as they may cause adverse reactions such as induration, sloughing, abscess formation, or severe pain at the injection site.
  - Such formulations are generally unsuitable for SC injection.