Choosing the Correct Needle to Give Yourself a Shot

Different injectable medications require different needles

Woman giving herself a shot
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If you are prescribed an injectable medication that you need to take on a regular basis at home, you will need to buy syringes and needles to administer your medication. A syringe is a clear tube that holds your medication right before you inject it, and a neede is the thin, sharp metal piece that you will insert into your skin.

Often, syringes and needles come separately and you can easily and securely attach them to each other. They come separately because you need to make sure that you get the right size syringe and the right size needle so that you can get the correct dose of medicine, inject it properly, and minimize pain.

Why You May Need To Inject Medication

There are a number of medications that you may need to inject at home, including medications for fertility procedures, vitamin B12 therapy, hormone medications, therapy for cancer, anti-inflammatory medications, and acute allergy treatments. You might need to administer the medication to yourself, administer medication to a family member, or you may need to have a family member learn how to inject you with your medicine.

Of course, your doctor or nurse will thoroughly go over the details of how to administer your injections at home, including telling you which syringes and needles to use and how to use them. Understanding some basic principles about needle and syringe sizing can help you avoid errors when you need to replace these items.

Syringe Sizes

Syringes are labeled based on how much liquid they can hold. Some syringes measure medication in milliliters (ml), others use cubic centimeters (cc), and some may be labeled with both scales. The good news is that 1 cc is equal to 1 ml, so you don't have to worry about confusing conversions when matching a syringe to your dosage.

If you will be injecting a medication at home, you need to make sure that you select a syringe that will hold the amount of medication you've been prescribed. For example, if you're supposed to give yourself 3 cc of a drug, you should be sure to get a syringe that holds exactly 3cc or just a little more than 3cc. If you use a syringe that holds only 2 cc, you would have to inject yourself more than once, which is unnecessarily painful. If you use a syringe that holds 15 cc, on the other hand, it can be hard to see the markings at the 3cc level with accuracy, and you could easily end up taking too little or too much medication.

Neede Sizes

Needles are labeled differently than syringes. The packaging will have a number, then a "G," and then another number. The first number, which is in front of the G, indicates the gauge of the needle. The higher the number, the thinner the needle. The second number indicates the length of the needle. For example, a 22 G 1/2 needle has a gauge of 22 and a length of an inch.

  • Needle gauge: If you will inject yourself with a small amount of medication, a thin, high gauge needle would work fine and should cause less pain than a wider, low gauge needle. However, for a larger amount of medicine, it can take an unnecessarily long time to inject using a thin, high gauge needle, so a wider, small gauge needle would be faster, causing less pain and discomfort.
  • Needle length: As far as the needle length, this depends on the size of the person, and where it needs to be injected. A young child would need a shorter needle than an adult, and a superficial injection requires a shorter needle than a deep injection.

There are two main types of shots that are used at home. Some medications are well absorbed superficially, directly underneath the skin, and others are absorbed in the muscles.

  • Subcutaneous injections go into the fatty tissue just below the skin. Since these are relatively shallow shots, the needle required is small and short—typically one-half to five-eighths of an inch long with a gauge of 25 to 30.
  • Intramuscular Injections go directly into muscle. Muscle is deeper than the subcutaneous layer of skin, so the needle used for intramuscular injections must be thicker and longer. The size needles that usually are best are 20 or 22 G needles that are an inch or an inch-and-a-half-long. The length of the needle also requires paying attention to the amount of body fat. Someone who's thin can usually use an inch-long needle and a person who's on the heavier side may need to use an inch-and-a-half-long needle.

A Word From Verywell

The most important thing to keep in mind when you need to give yourself an injectable medication is that your doctor or another medical professional who's involved in your care will be happy to help you if you get stuck figuring out which needles or syringes to use or how to give yourself a shot.

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