What are the common approaches for basic injections in a general medicine clinic?

Basic Injection Techniques in General Medicine Clinic

Needle Selection and Insertion Technique

For subcutaneous injections, use 4-mm needles inserted at 90 degrees for all adults regardless of age, sex, ethnicity, or BMI. 1 This is the safest needle length with minimal risk of intramuscular or intradermal injection. 1

• Very young children (≤6 years) and very thin adults (BMI <19) should lift a skinfold when using 4-mm needles to ensure subcutaneous delivery. 1
• For needles longer than 4 mm, a correctly lifted skinfold must be used to avoid intramuscular injection. 1
• Subcutaneous injections can alternatively be administered at a 45-degree angle into the thigh or upper-outer triceps area using a 5/8-inch, 23-25 gauge needle. 1

For intramuscular injections, use needles at 90 degrees with length appropriate to patient body habitus. 1, 2

• Adults require a minimum needle length of 1½ inches for gluteal injections; obese patients may require longer needles. 3
• For deltoid injections in toddlers and older children, use 22-25 gauge needles ranging from 7/8 to 1¼ inches based on muscle mass. 1
• For infants, use 7/8 to 1-inch, 22-25 gauge needles in the anterolateral thigh. 1

Recommended Injection Sites

Subcutaneous injections should be administered in four primary sites: 1

• Abdomen: 2 adult fingerbreadths (approximately 1 cm) away from the umbilicus, staying 1 cm above the symphysis pubis and 1 cm below the lowest rib. 1
• Thigh: Upper third anterior lateral aspect of both thighs. 1
• Buttocks: Posterior lateral aspect of both upper buttocks and flanks. 1
• Upper arm: Middle third posterior aspect of the upper arm. 1

Intramuscular injections should target specific muscle groups: 1, 2, 3

• Deltoid muscle (middle third posterior aspect of upper arm) for adults and children with adequate muscle mass. 1, 2
• Anterolateral thigh (upper third anterior lateral aspect) for infants and as an alternative site. 1, 2
• Gluteal muscle for systemic medications requiring deep injection (adults only). 3
• Ventrogluteal area (upper outer buttock region) as an alternative site. 2
• Never use the buttock for vaccines or toxoids due to risk of sciatic nerve injury and decreased immunogenicity. 1

Site Preparation and Hygiene

Injections should be given into clean sites using clean hands. 1

• In noninstitutional settings (homes, restaurants, workplaces), disinfection is usually not required. 1
• In institutional settings (hospitals, nursing homes), disinfection is mandatory. 1
• If alcohol is used for disinfection, it must be allowed to dry completely before injection. 1
• Cleansing the needle with alcohol may remove the silicon coating that reduces pain and is not recommended. 1

Site Rotation and Contraindications

Correct rotation of injection sites must be followed at all times to prevent lipohypertrophy. 1

• Rotate within one anatomical area (e.g., systematically within the abdomen) rather than rotating to different areas with each injection to decrease absorption variability. 1
• Move injections at least half an inch (1 cm) away from the previous injection site. 1

Never inject into the following sites: 1

• Areas of lipohypertrophy (lumpy, firm, enlarged tissue)
• Sites with inflammation, edema, ulceration, or infection
• Scars or damaged tissue
• Areas within a 2-inch radius around the navel for insulin injections 1

Injection Procedure

Follow this systematic approach for safe injection administration: 1

1. Verify the medication label before each injection to avoid administering incorrect medication. 1
2. Prepare the dose on a clean workspace with appropriate hand hygiene. 4
3. Inspect for air bubbles after drawing medication; flick the syringe to allow bubbles to escape. 1
4. Lightly grasp a skinfold if required based on needle length and patient body habitus. 1
5. Insert the needle in a smooth motion (not jabbing) at the appropriate angle. 1
6. Routine aspiration is not necessary for most injections. 1
7. Inject slowly to minimize discomfort, ensuring complete dose delivery. 1
8. For pen injections, count to 10 after depressing the button before withdrawing the needle. 1
9. Dispose of needles immediately in labeled, puncture-proof containers. 1

Common Pitfalls to Avoid

• Do not reuse needles or syringes between patients to prevent transmission of blood-borne diseases. 1
• Do not leave pen needles attached after use, as this can cause air entry or medication leakage. 1
• Do not touch the pen thumb button until the needle is fully inserted to avoid premature dose delivery. 1
• Do not inject cold medication as this increases pain; allow medication to reach room temperature. 1
• Do not inject into the same site repeatedly as this causes lipohypertrophy and unpredictable absorption. 1

Special Considerations

Patients should be educated that: 1

• Occasional sharp pain during injection may occur if the needle touches a nerve ending; this is random and causes no damage. 1
• Mild bleeding or bruising does not affect medication absorption or disease control. 1
• Some mild pain may be experienced when injecting into normal tissue after avoiding lipohypertrophic areas. 1
• Insulin will not be well-absorbed if always injected into the same area. 1