Welcome to brain Stuff, a production of iHeart Radio. Hey brain Stuff, Lauren Vogel Bomb Here. When you walk into a doctor's office to get a shot, as sometimes it's a surprise. Most of the time you can count on getting an injection in your arm, but occasionally they'll pitch you a curveball and injected into your rear end or even your belly. So why is this? It generally has to do with the type of medicine being injected, the volume of the dose, and how quickly or slowly the
medicine needs to be absorbed into the body. So today let's talk about the four basic types of medical injections. And if you don't like hearing about needles, but you've made it this far, now might be a good time to stop or skip to the next episode. Okay, okay. The first category we're talking about is intravenous injections. These go directly into the vein and deliver medicine really quickly. They're normally delivered in the back of the hand or
the front of the elbow. Next up, intramuscular shots. These are injected directly into a muscle where the medicine is absorbed a little more slowly by blood vessels. The most common locations for these are the deltoid muscle of the shoulder that's the meaty bit above the bicep, and the gluteous medius of the bum, which is the meaty bit at the upper outer quadrant of each buttock. In young children who may not have developed these muscles yet, the
thigh muscle might be used instead. Then we've got subcutaneous injections. These are given into fatty tissue where there's less blood supply and therefore the medicine is taken up by the body more slowly. These are generally injected into the abdominal fold. And finally, there are intradermal injections. These target the middle layer of the skin and are absorbed the most slowly
of all. Common injection sites for these include the inner surface of the forearm and the upper back under the shoulder blade for the article of this episode is based on how stuff Work. Spoke with Libby Richards, a faculty associate at the Perdue University School of Nursing. She explained the injection site is driven by how the medication is absorbed. Some medications, like insulin, need to be absorbed slowly, so
fatty tissue without much blood flow works better. Medications injected into the muscles are absorbed faster than fatty tissues, but slower than intravenous. For example, it's coming for antibiotics and diuretics to be administered intravenous LYE, whereas many vaccines, hormone shots, and allergy medications are injected intramuscular LYE. Vaccines are often injected into muscles because muscles contain more immune cells than
other injection sites. These immune cells will immediately recognize the stuff that makes the vaccine work, uh the weakened or non operational or otherwise non infectious bits of virus material that the vaccine contains, so those cells will quickly start to prepare your body to fight the real thing should it invade. In addition to the type of medicine, doctors and nurses need to think about how much medicine needs to be injected and whether a specific muscle is large
enough to hold that much medication. Richard said, a muscle tissue can generally hold more volume than fatty or subcutaneous tissue, so that's another consideration when choosing an injection site. When the volume of medication is a consideration. A larger muscles such as the buttocks or thigh may be used instead of the arm. Plus some medications can cause irritation to delicate blood vessels. In this case, muscle is preferred as well.
And even with all of these considerations, you can still ask your doctor if they can give you an injection in your preferred location, Richard said, Sometimes it comes down to patient preference and convenience. The arm is often easier to access and preferred by patients. M Today's episode is based on the article why are some shots given on the arm and some in the bum? On how stuff works dot com written by Jocelyn Shields. Brain Stuff is production of by Heart Radio in partnership with how stuff
works dot Com and it's produced by Tyler Clang. Four more podcasts my heart Radio, because at the heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows