Injecting medication and supplements can be painful and perhaps dangerous if it isn't done correctly. The injection techniques you use should vary for each part of the body or type of injection. The angle of the needle entry is important for all types of injections as it is the key to reducing pain. For example, intramuscular injections need the needle at a 90-degree angle to ensure it reaches the muscle without having to shear through the tissues and therefore cause unnecessary pain.
When delivering an intradermal injection under the skin for a local, rather than systemic effect, use a 25-gauge needle inserted at a 10-15-degree angle. Inject up to .5 mL. This type of injection is used primarily for allergy testing, tuberculin testing, or delivering local anesthetics.
When injecting into the skin for a subcutaneous injection, such as for insulin which requires a slow and steady release, the needle should be held at a 45-degree angle if it is the traditional length needle, or at 90-degrees if it is a shorter insulin needle of 5, 6, or 8mm. The skin of the injection site should be pinched and raised before needle insertion to lift the adipose tissue away from the muscle, especially important for thin patients.
An injection directly into the muscle provides a rapid systemic action and is used for absorption of large doses. The choice of injection site should take into consideration the physical condition of the patient and the size of the dose.
There are five sites for intramuscular injections:
Upper Arm – the deltoid muscle, often used for adult vaccinations.
Dorsogluteal – the gluteus maximus muscle. Care must be taken when injecting in this area to avoid damaging the sciatic nerve.
Ventrogluteal – the primary site for intramuscular injections, in the gluteus medius muscle. It avoids all nerves and blood vessels.
Quadriceps – the vastus lateralis is in the quadriceps located on the outside of the femur and is used primary as an injection site for babies and children.
Rectus femoris - in the anterior quadriceps muscle, is often used for self-administration of medication or for infants.
When administering an intramuscular injection, you first prepare the syringe by releasing excess air, leaving about .1 to .2 mL of air in the syringe. Spread the skin of the injection site with the fingers of your non-dominant hand. Hold the syringe with your dominant hand and enter the muscle at a 90-degree angle. Slowly inject the medication at a constant rate until the dose has been fully delivered and withdraw the needle and syringe quickly.
Intravenous injections are much more complicated and dangerous than all other types of injections. Using an improper technique can lead to infection and other problems. To minimize damages, clean the injection site with isopropyl alcohol first. Wrap a tourniquet around your arm above the injection site, and insert the needle with the flow of the vein at a 45-degree angle. Pull the plunger back a bit to see if there is any blood – if there isn't, it means you missed the vein. Once you have the vein, remove the tourniquet. Never administer medication while the tourniquet is in place as the vein can burst from the pressure. Push the plunger slowly to administer the medication.