What Happens If You Give a Subcutaneous Injection Intramuscularly?

What Happens If You Give a Subcutaneous Injection Intramuscularly

When giving medication through injections, precision is very important. The smallest mistake between delivering a subcutaneous injection into the fatty tissue just below the skin, and an intramuscular injection, which penetrates the muscle tissue, can have vastly different outcomes.

Any healthcare professional or a doctor will tell you that the subtle difference between the two is critical. But what exactly happens if you give a subcutaneous injection intramuscularly?

In this article, we explain to you what happens if you give an injection under the skin into the muscle by mistake. We’ll also give you some tips on how to properly administer a subcutaneous injection to avoid mistakes and keep patients safe.

The difference between Subcutaneous and Intramuscular injections

It’s very crucial to know the distinction between subcutaneous and intramuscular injections for the safe administration of various medications.

Each method targets a different layer of the body’s tissue, influencing both the absorption rate and effectiveness of the medication administered.

What is Subcutaneous Injections?

The Subcutaneous injections are administered into the fatty layer of tissue that lies between the skin and the muscle.

These injections go under the skin, not deep like muscle shots. Subcutaneous injections are often used for medicines that require slow, sustained absorption into the bloodstream.

Therefore, they are very effective for delivering vaccines, growth hormones, and insulin, ensuring a continuous low dose. Subcutaneous injections are also preferred for some pain relievers like morphine and hydromorphone, as well as allergy medications.

These drugs can be administered through a single syringe injection or long-term infusion via a skin-installed pump.

How its work?

Subcutaneous injections bypass the stomach and digestive processes and allow for more direct access to the bloodstream. This is especially important when a patient has gastrointestinal issues, which may interfere with medication absorption.

What is Intramuscular Injections?

Intramuscular injections are delivered directly into a muscle, where they can be absorbed quickly by the blood vessels that run within the muscle tissue.

This method is often used for medications that require rapid absorption into the bloodstream or for drugs that are too irritating to be administered subcutaneously. Vaccines, antibiotics, and hormonal therapies often utilize this route due to its fast-acting nature.

How it works?

The muscles have a richer blood supply compared to the fatty layer under the skin, facilitating a quicker onset of medication action. This method is very beneficial for emergency medications, where an immediate effect is critical.

Furthermore, because muscles can hold a larger volume of fluid without discomfort, intramuscular injections can deliver doses of medication that are too large for subcutaneous routes.

Also Read: Bubble Under the Skin After Ozempic Injection

What happens if you give a subcutaneous injection intramuscularly?

It may lead to various negative outcomes if you mistakenly give subcutaneous injections into the muscle, depending on the medication’s nature and the injected volume.

Firstly, when a drug gets absorbed faster, it might start quicker or have stronger effects on your body which may not be what you want all the time.

Secondly, some medicines are made to slowly come out from under the skin. Giving these medicines to the muscle instead might change how they come out, which could make the medicine not work as well or not be safe.

Additionally, intramuscular injection could cause irritation, discomfort, or damage inside the muscle tissue, especially if the medication is not meant to be delivered intramuscularly.

Lastly, there’s a risk of injection-site reactions, like pain, swelling, and muscle stiffness, which could impair the patient’s mobility and comfort. Therefore, it’s crucial to ensure the proper administration method is used for each type of injection to avoid any problem and ensure patient safety.

Consequences of Giving a Subcutaneous Injection Intramuscularly

Giving a Subcutaneous Injection Intramuscularly

If you give an injection under the skin into the muscle by mistake, what happens can change a lot. It depends on things like the medicine, how much you take, and your health.

Still, a few usual results show why it’s crucial to use the right shot technique.

1. Changed Medicine Movement: Shots into the muscle usually make the drug work faster than injection under the skin. This might make the drug reach its needed level too soon, which could lead to an overdose or more side effects.

2. Reduced Efficacy of the Medication: Some medicines are made to slowly enter the bloodstream from the fat layer under the skin. If they are absorbed quickly through the muscle, the drug may run out faster than expected, making it less effective or requiring more frequent doses.

3. Tissue Damage and Irritation: Medications designed for subcutaneous injection often contain agents that can irritate or damage muscle tissue. This may cause pain, swelling, tissue death, and even lasting muscle problems, making patients uncomfortable and possibly causing issues.

4. Injection-Site Reactions and Complications: Incorrectly administered injections increase the chances of reactions at the injection site. This includes severe soreness, swelling, bruising, and even infections.

5. Immune System Activation: Some medications, when injected into the muscle, can extract a stronger immune system response. While this may be beneficial for certain vaccines, for other drugs it can lead to unnecessary complications, like allergic reactions or the formation of antibodies that reduce the drug’s effectiveness.

Signs of Improper Injection Administration

You must know about the signs of improper injection administration for early action and to avoid complications. Here are some common signs which include:

  • Persistent or Severe Pain: While some discomfort is normal, pain that persists for days or is unusually severe may show that the injection was not given correctly.
  • Swelling or Hardening of the Injection Site: Some swelling is expected, but if the area becomes excessively swollen or hard, it could be a sign of tissue irritation or damage.
  • Redness and Warmth: These are signs of inflammation that may occur with improper injection techniques. If the redness spreads or the warmth increases over time, it might indicate an infection.
  • Bruising: While small bruises are relatively common, large areas of bruising can occur when an injection damages blood vessels.
  • Fever or Illness Symptoms: Unexpected fever, chills, or feeling unwell after an injection could suggest an adverse reaction to the medication or an infection at the injection site.

If you observe any of these signs, it is important to contact a healthcare provider immediately for assessment and guidance.

How to give a Subcutaneous Injection correctly

Administering a subcutaneous injection correctly is vital for the effectiveness of the medication and the comfort of the patient. Here are simple steps to make sure you do a safe and proper subcutaneous injection:


  • Verify the Medication: Confirm that you have the correct medication and dosage.
  • Gather Supplies: This includes the pre-filled syringe or vial, a needle (usually 25-30 gauge, 5/8 inch), alcohol wipes, and a sharps disposal container.
  • Hand Hygiene: Wash your hands completely with soap and water or use an alcohol-based hand sanitizer.

Selecting an Injection Site:

  • Choose an area with sufficient subcutaneous tissue, usually the upper arms, thighs, abdomen (at least 2 inches away from the belly button), or the upper back portion of the hip. Rotate the sites to prevent tissue damage.

Prepare the Injection:

  • If using a vial, clean the top with an alcohol wipe. Draw the prescribed amount of medication into the syringe.
  • For pre-filled syringes, remove the cap and check the medication for any discoloration or particles.

Clean the Injection Site:

  • Use an alcohol wipe to clean the skin where you’ll inject the medication. Allow it to dry completely to reduce the risk of infection.

Injecting the Medication:

  • Hold the syringe like a pencil, with the needle poised at a 45 to 90-degree angle to the skin, depending on your healthcare provider’s advice.
  • Gently pinch up a fold of skin at the injection site. Insert the needle in one swift motion.
  • Once the needle is fully inserted, push the plunger slowly and steadily until all the medication is injected.
  • After injecting, release the skin fold and withdraw the needle. Dispose of it immediately in a proper sharps disposal container.


  • Do not rub the injection site. You may gently apply a clean bandage if there is bleeding.
  • Monitor the site for any signs of reaction, like excessive redness, swelling, or pain.

Importance of Proper Training and Technique

Proper training and technique in administering injections are crucial for several reasons:

1. Safety: Ensures that medications are given in a way that maximizes their effectiveness while minimizing any potential harm to patients. Knowing the correct method helps avoid mistakes that can cause serious health issues.

2. Reduce Complications: Correct technique reduces the risk of complications like infections, tissue damage, or unwanted side effects. It gives better patient outcomes and overall satisfaction.

3. Comfort: Using the right methods can make patients feel less pain, discomfort, and worry. When patients feel less pain, they are more likely to follow their treatment plans.

4. Efficiency: Properly administered injections work as they’re supposed to, meaning patients get the full benefit of the medication without needing unnecessary repeat doses.

5. Minimize Waste: Knowing how to administer injections correctly means less medication is wasted, which is important for expensive treatments.

Prevention and Best Practices

Knowing the body parts where injections are supposed to go is important to avoid issues. For injections just under the skin, it’s better to choose spots like the upper arms, thighs, or belly because these areas have enough skin underneath and less chance of hitting muscle or bone.

1. Proper Injection Technique: It’s important to use a method that reduces pain and tissue harm. This means using the right needle length—long enough to reach below the skin but not too long to go into the muscle. The “pinch-up” technique involves pinching the skin to create a fold, ensuring that the injection goes into the fatty layer beneath the skin, not the muscle.

2. Sanitation and Hygiene: Keeping things clean is super important. Making sure to wash your hands properly, clean your skin where you’re getting the injection, and always use a new, sterile needle for each injection helps prevent infections and cross-contamination.

3. Patient Education: Teaching patients why it’s important to follow their treatment plan, how to inject correctly (if needed), and spot problems early is important. Knowing this stuff can help avoid mistakes and catch issues sooner.

4. Keeping Up with Training for Healthcare Providers: Healthcare workers should keep learning to stay updated on the newest injection methods and rules. Training with simulations is a good way to practice skills in a safe place.

5. Patient Positioning and Comfort: Making sure the patient is comfy and relaxed can really help their experience and make giving injections easier. Feeling anxious or tense can make pain worse and increase the chance of problems.

Healthcare providers can lower risks when giving injections by using prevention methods. This helps medicines work better and keeps patients safe and trustful.

Myths Related to Injection Administration

Many myths about getting shots can make people scared and skip important medical care. Let’s clear up some common misunderstandings:

1. Bigger Needles Are Better: Don’t think bigger needles are always better – that’s a myth. Pick the needle size that matches the injection type and the patient’s body. Smaller needles work fine for just under-the-skin shots and can reduce pain and tissue damage.

2. Injections Deliver Medication Instantly:  Injections are faster than pills, but they don’t act right away. The time it takes for the medication to start working depends on the injection type and how the drug moves in the body.

3. More Medication Means Faster Recovery: Doctors give the right amount of medicine based on your weight, age, and what’s wrong. Taking extra medicine won’t help you get better faster and could make you feel worse.

5. Alcohol Swabs Are Optional: The use of alcohol wipes is important for sanitizing the injection site and preventing infection. Skipping this step can introduce bacteria into the injection site and lead to complications.

Key Points to Remember

When giving injections, it’s crucial to know the medication’s pharmacological principles.

1. Pharmacokinetics and Pharmacodynamics: Understanding how a drug is absorbed, distributed, metabolized, and excreted (pharmacokinetics), as well as its mechanisms of action and effects on the body (pharmacodynamics), can guide the choice of injection site, and method, and timing for optimal efficacy and minimal side effects.

2. Viscosity of Medication: The thickness of medication affects needle size and injection force. Thicker meds might need bigger needles for easier injection.

3. Volume of Medication: The amount of medication you need to give is important in choosing where to inject and how to do it. Some spots can only handle small amounts comfortably and safely.

4. Anatomical Considerations: Specific anatomical landmarks should be identified to avoid nerve damage, blood vessels, and bone. Proper anatomical knowledge can significantly reduce the risk of complications.

By including these things in shots, doctors can make patients safer, help medicines work better, and make patients happier with their treatment.


In conclusion, getting the right techniques and following the best ways to give injections is super important for keeping patients safe, and comfy, and making treatments work well. Clearing up misunderstandings and teaching healthcare providers and patients about injections can make healthcare better. By focusing on training, cleanliness, and caring for patients, healthcare pros can lower risks and make things better for those they’re helping.


What happens if you do a subcutaneous injection wrong?

Doing a subcutaneous injection incorrectly can cause several problems, like pain at the site, infection, or improper absorption of the medication. This can result in the medication not working as intended, requiring additional doses, or causing unwanted side effects. Ensuring proper technique is crucial for the effectiveness and safety of the treatment.

What happens if you give a subcutaneous injection too shallow?

Giving a subcutaneous injection too shallow can cause the medication to be injected into the skin rather than the fatty tissue layer below. This mistake can cause a local reaction at the injection site, like irritation, redness, or a hard lump, known as a “localized site reaction”.

Are there any specific symptoms indicating that a subcutaneous injection has been given intramuscularly?

Yes, if a subcutaneous injection is accidentally given intramuscularly, several symptoms may indicate this error. These include increased pain at the injection site, swelling, and possibly a faster absorption rate of the medication than intended. Unlike subcutaneous tissue, muscles have more blood vessels, which can cause quicker medication dispersion and potentially increase the risk of systemic side effects.

Can patients administer subcutaneous injections on their own, and if so, what training is required?

Yes, patients can administer subcutaneous injections on their own with proper training and guidance. The training should teach how to pick the right spot for the shot, throw away the needle safely, and inject yourself correctly to reduce pain and infection risks. It’s best to practice with a healthcare professional watching to feel confident and do it right.



The information provided in this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Don’t ignore professional medical advice or put off seeking it just because of something you read here. Although we aim to offer precise and current information, we do not guarantee its completeness, accuracy, reliability, suitability, or availability for any purpose. Using the information in this document is at your own risk. We are not responsible for any losses or damages caused by our content.

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