A subcutaneous injection or shot is one into the fatty tissues just beneath the skin. These injections are shallower than those injected into muscle tissues.
Subcutaneous injections are usually safe and do not require as much force as intramuscular injections into the muscle tissues.
Subcutaneous injection can be used to give many types of medications for various medical conditions.
There are fewer blood vessels in the fatty layer of connective tissue just beneath the skin than the muscle tissue.
Having fewer blood vessels means that medication injected subcutaneously is absorbed more slowly.
This makes it an ideal way to administer medications that the body must use slowly over time, such as insulin for the treatment of diabetes.
Medications given this way include:
- insulin for diabetes
- blood thinners, such as heparin
- some fertility drugs
- some drugs, such as Enbrel and Kineret, for autoimmune diseases, including arthritis.
Many drugs that must be taken daily, or injected at home, are designed for subcutaneous injection.
To give a subcutaneous injection, people should follow these steps:
- Choose a fatty area of the body, such as the abdomen, back of the arm, or thigh: If you are giving several injections or have to do daily injections, rotate the sites to allow each area to heal between injections
- Wash hands before cleaning the area with an alcohol pad: Wait for the area to completely dry before the next step.
- Take the cap off the needle: Draw medication into the syringe, according to the directions on the vial. This usually means turning the vial upside down then pulling the plunger back to suck in the medication. Tap the syringe to get rid of air bubbles.
- Pinch a fold of skin: Pinch the fatty area about 2-inches thick in between the thumb and a finger.
- While holding the needle like a dart, slide it into the skin at an angle of 90 degrees: Needles used for subcutaneous injection are usually short and small and should go all the way into the skin.
- Push the plunger all the way down quickly: Do not push forcefully.
- Cover the needle: Dispose of the needle in a needle-safe container.
The best location for a subcutaneous injection depends on a person’s pain sensitivity and where they have some subcutaneous fat.
A few commonly chosen locations include:
- the backs or sides of the arms
- the fatty part of the stomach
- the front of the thighs
- the top of the buttocks, where there is more fat than muscle
Some subcutaneous injections come in the form of an auto-injector. An auto-injector is a self-contained device that does not require drawing the medication up first. People can follow the instructions on the package if they are using an auto-injector.
The needle used for subcutaneous injection is usually small and short and causes minimal discomfort.
The amount of pain a person feels depends on factors such as where they or another person administer the injection, their pain tolerance, and skin sensitivity.
The pain also depends on the medication they are injecting, as it may cause stinging, burning, or aching during or following the injection.
Subcutaneous injections tend to be less painful than intramuscular injections because the needles are smaller and do not have to push through as much tissue.
Children and people who fear needles may still have issues with these injections that can cause anxiety.
A few strategies can help with the pain and anxiety:
- Use a numbing cream on the area a few minutes before the injection. Many doctor’s offices have these available.
- Try putting ice on the area to numb it a few minutes before the injection.
- Allow nursing babies to breast-feed during injections.
- If a child needs restraining, hold them in a hugging way rather than holding them down or yelling at them.
- Give a baby a pacifier before an injection.
- Cough or blow before or during the injection.
- Take five deep breaths or encourage children to breathe deeply before the shot.
- Distract yourself with a movie, video game, or conversation. Sometimes looking at the shot makes it hurt more.
The most common complication of a subcutaneous injection is pain near the injection site for 1 to 2 days afterward.
Pain near the injection site can happen when inserting the needle at the wrong angle, or when it moves slightly during the injection. Some medications can cause a bruise or irritation at the injection site.
Other complications are much less frequent and include:
- Infection: Any puncture in the skin can allow bacteria to enter and cause an infection. Properly cleaning the area and always using a clean needle can reduce the risk of infection.
- Contaminated needle: Reusing needles or sharing needles can spread diseases from one person to another. Always dispose of used needles in an appropriate container.
- Injecting medication into a blood vessel: A person may have hit a blood vessel if there is blood in the syringe. Injecting medication into a blood vessel can change the way the drug is absorbed.
Injecting a blood vessel can cause serious complications in rare cases. However, the likelihood of hitting a blood vessel in the subcutaneous fat is extremely rare. More than likely, if there is blood, it is from slight bleeding after the injection.
A subcutaneous injection is a minor and very safe medical procedure when done correctly.
Mastering the technique of injecting at home can take some practice. People should ask for help from a medical provider and not shy away from asking questions about the benefits of treatment or how best to minimize pain.