Subcutaneous injection: what is it and how to give one

Subcutaneous injections, which are injections administered just under the skin, can be used to deliver a wide range of medications. They offer the added benefit of being a straightforward way for people who need frequent injections to get their medicine at home without visiting a healthcare provider.

These injections are common in people who have diabetes requiring insulin administration. Many fertility drugs and certain treatments for arthritis, multiple sclerosis, and cancer can also be administered subcutaneously (Woodley, 2022).

No matter how common this medication delivery method may be, injecting yourself (or someone else) may be intimidating. But with guidance from a healthcare professional, you can learn to give medications subcutaneously on your own.  

Here’s a look at how subcutaneous injections work and what to expect. 

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Subcutaneous means under the skin. A subcutaneous injection—also called a sub-Q or SQ injection—goes just under the skin and into that layer of fat above the muscle. These injections are typically less painful than intramuscular injections, which go into the muscle (requiring longer needles) (Usach, 2019).

In addition to being relatively painless, SQ injections are easy to do at home, and the small needle size means the risk of infections is low (Usach, 2019).

Compared to intramuscular or intravenous (into a vein) injections, subcutaneous injections deliver medications more slowly, which is important for certain medications. For instance, in the case of an insulin injection for diabetes, slower medication delivery means a more effective and even control of blood sugar. 

There are several common subcutaneous injection sites, all of which are places on the body with a layer of fatty tissue under the skin. These include the outer surface of the upper arm, the upper area of the front of the thigh, the abdomen (two inches from the belly button), and the buttocks (MedlinePlus, 2021). Where you inject your medication will depend on your healthcare provider’s instructions.

If you are giving yourself or another person daily or weekly injections, your healthcare provider may recommend switching up your injection site each time or positioning the needle at least one inch away from the last place you injected. Repeatedly using the same spot can cause a sort of scar-like tissue to form, which may make it more difficult for your body to absorb the medication injected there. It can also cause bruising (Kim, 2021). 

Your healthcare provider will go over the specifics for your particular medication, including how to store the medication (in the refrigerator or at room temperature), the dosage, when to inject, and details about the injection device you’ll be using. 

Likewise, if you’re helping someone else with their injections, follow their healthcare provider’s exact instructions. Some medications have very specific dosing requirements based on weight and other factors unique to each person.  

There are different types of injection devices, so it’s important to know ahead of time what type you’ll be injecting. Some come prefilled with an exact dose for one-time use. Others contain multiple doses or need to be refilled. There are also pen-like injection devices that deliver medication with the click of a button (FDA, 2013). 

Yet another type of injection device is called an autoinjector, best known with EpiPens, a quick-jab method of delivering epinephrine into the muscle for people having a severe allergic reaction (Campbell, 2016). Autoinjectors come in a variety of styles and are also used for subcutaneous injections of other medications (Tornero-Molina, 2021). 

Many medications come in vials or containers that need to be transferred to a syringe. These typically use disposable needles and syringes.

Taking stock of supplies

Before any injection, it helps to have your supplies laid out on a clean, dry surface. Supplies  typically include:

• Medication and sterile disposable needles/syringes (or a prefilled injection device combining both)

• Alcohol pad or cotton ball with rubbing alcohol (isopropyl or ethanol alcohol)

• A puncture-proof container for safe needle disposal (as needed)

• A band-aid

The steps taken to give yourself or another person a subcutaneous injection are based on the device you are using. Always follow the instructions from your healthcare provider. 

Here are some standard approaches:

• Wash your hands thoroughly with soap and water.

• Cleanse the injection site with a fresh alcohol wipe or cotton ball soaked in alcohol; wait 30 seconds for the site to dry before injecting.

Injection using a pen injector or autoinjector

If using a pen injector or another prefilled injection device, follow your provider’s instructions. Here’s some more information to help guide you (FDA, 2013):

• If the device is prefilled with the exact dosage, your healthcare provider will instruct you to hold the pen to the skin’s surface and push the button on the top. For autoinjectors, the force of the injector hitting the skin activates the needle.

• Multi-use injectors have a dosing dial to ensure the correct dose is given. It’s important to discuss dosing and how to set the dial with your healthcare provider.  

• Some pen injectors have snap-on disposable needles; others have built-in retractable needles.

• After the injection, see directions about disposal or storage. Disposable needles will need to be put into a puncture-proof metal or hard plastic container, often called a “sharps container.”

Injection using a disposable needle/syringe

As with prefilled injection devices, consult with your healthcare provider about medication dosing and delivery. 

The following are some basics instructions for using a needle and syringe (MedlinePlus, 2021; WHO, 2010):

• Remove the needle cap.

• Draw up the amount of medication needed (refer to instructions) using the syringe's plunger; this may mean turning the vial upside down.

• Tap syringe to clear air bubbles. You may need to push the syringe plunger slightly to clear air from the syringe (air displaces the medication, potentially reducing dosage).

• Pinch a 2-inch fold of skin, avoiding the muscle below (fat and skin only).

• Hold the syringe with the index finger like a pencil or dart. 

• Insert the needle with the opening of the needle (called the bevel) facing up at a 45- to 90-degree angle to the pinched skin. A45-degree is usually better in areas where there isn’t much fat, but always follow your healthcare provider’s instructions).

• Insert the needle so that it’s completely covered by skin.

• Once it’s inserted, slowly push the plunger to inject the medication. 

• Do not rub or massage the area.

• If there is bleeding, apply a bandage.

• Place the used needle in a sharps container.

The very thin needles used nowadays have made subcutaneous injections less painful. Here are some other ways to reduce discomfort, if needed (Usach, 2019):

• Ask your healthcare provider if you can apply a topical anesthetic, like benzocaine, before injection.

• Make sure the needle is beveled side up, meaning you can see the oval-shaped hole if the injection is at an angle because it will help the needle slide in more easily.  

• If using a syringe, push the plunger down slowly rather than quickly. The slower entry of medication doesn’t fracture tissue as much and may lessen bruising (Kim, 2017).

It’s normal to have some pain or bruising for a day or two where you injected the medication, depending on the medication. Your healthcare provider can help you understand what to expect from your medication.

The chances of injecting the medication into a blood vessel in subcutaneous fat are low but possible (Sepah, 2017). If this happens, you may notice blood in the syringe. This is generally not a cause for concern, but it can change how quickly medication takes effect in some cases. Call your healthcare provider if you have any questions or have unexpected medication side effects. 

Getting an infection from a subcutaneous injection is rare, but be sure to contact your healthcare provider if you experience fever, redness, warmth, or pain at the injection site in the days following an injection. These could be signs of an infection (Zhu, 2019). 

Every medication comes with instructions that are often tailored to the individual. It’s important to consult with your healthcare provider about all medications, dosing, and how to give a subcutaneous self-injection if that’s required for treatment. 

Your healthcare provider may have you inject your first doses in their office so you can get comfortable with it. That gives you a chance to get feedback and tips. It takes some getting used to but giving yourself or someone else a subcutaneous injection gets easier with practice.

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Current version

February 16, 2022

Written by

Kristin DeJohn

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.