Why are some injections given in the arm and others in the buttocks?

When you go to the hospital for an injection, you will be prepared to inject into your hand, but sometimes doctors will surprise you a little when they decide to inject. the buttocks or even the abdomen. Why is that?

Pull up your sleeves or pull down your pants

The site of injection is often related to the type of drug to be injected, the dose of the drug, and the rate at which the drug needs to be absorbed into the body.

There are different ways to get drugs into the body with a needle:

1. Intravenous injection: The drug enters the body very quickly by going directly into the bloodstream. The drug is usually injected into the back of the hand or the front of the elbow.
2. Intramuscular injection: Injected directly into a muscle bundle, where the drug will be absorbed slightly more slowly by the blood vessels. The most common sites for injection are the deltoid muscle of the shoulder or arm and the gluteus medius muscle of the buttocks, or thigh muscle, or vastus lateralis, in young children.
3. Subcutaneous injection: injected into the middle layer of the skin and has the slowest absorption rate. Common injection sites include the inner surface of the forearm and the upper back, below the shoulder blades.

Common injection sites.

Not all injections are created equal

"The area of ​​injection is determined by how the drug is absorbed," said Libby Richards, an associate professor at Purdue University School of Medicine. 'Some drugs, like insulin, need to be absorbed slowly so fatty tissues with less blood flow would be a better choice. Drugs injected into muscle are absorbed faster than fat tissue, but slower than intravenous injection.

For example, for antibiotics, diuretics, and pain relievers, doctors usually inject them into a vein; while many vaccines, hormones, and allergy medications are injected into the muscle.

In addition to the drug, doctors and nurses also need to take into account the amount of drug that needs to be injected, and whether a particular muscle group is large enough to hold that amount.

'Muscle tissue can usually hold more drug than fat or subcutaneous tissue, so this is another factor to consider when choosing the injection site. When the amount to be injected is large, large muscles such as the buttocks or thighs may be selected instead of the arms. Plus, some drugs can irritate delicate blood vessels - in which case muscle injections would be preferred,' Richards said.

Still, you can still ask your doctor if they can inject into the area of ​​your choice: 'Sometimes, the decision depends on the patient's wishes and convenience. The arm is often more accessible and is also the place of choice for patients more, "- Richards said.