What Causes an Incorrect Intramuscular Injection Illustration

What Causes an Incorrect Intramuscular Injection? (2023)

by | Updated: Sep 24, 2023

Intramuscular injections, a common medical procedure, involve the delivery of medication deep into the muscles, allowing for quicker absorption and faster onset of action compared to oral administration.

While this method is generally effective and safe, it is susceptible to errors, potentially leading to adverse events or compromised efficacy.

Incorrect intramuscular injections can result from various factors, ranging from improper injection site selection to incorrect needle length or inappropriate injection technique.

Understanding the factors that can cause an incorrect injection is pivotal for healthcare providers to mitigate risks and ensure the optimal benefit of administered medications.

What Causes an Incorrect Intramuscular Injection?

Incorrect intramuscular injections can be caused by a variety of factors, including improper site selection, inappropriate needle length, and incorrect injection technique. These errors may lead to complications such as pain, infection, tissue damage, or suboptimal medication absorption, highlighting the importance of precise adherence to injection protocols and guidelines by healthcare providers.

Incorrect Intramuscular Injection Vector Illustration

What is an Intramuscular Injection?

An intramuscular injection is a technique used to deliver medications directly into a muscle.

This method allows the rapid absorption of medication into the bloodstream, making it a suitable choice for medications that require quick onset of action or those not suitable for oral administration.

It involves inserting a needle through the skin, subcutaneous tissue, and into the muscle layer, and it is essential that this procedure is carried out accurately to avoid complications. 

Intramuscular Injection Sites

Intramuscular injection sites are selected based on factors such as age, medication type, and muscle mass.

The most common sites include:

  • Deltoid Muscle (Upper arm): Commonly used for small-volume injections, such as vaccines.
  • Vastus Lateralis Muscle (Thigh): Preferred for infants and children, but also suitable for adults. Often used for large-volume injections or medications that may be irritating to tissues.
  • Gluteus Medius Muscle (Hip): Suitable for large volumes and viscous medications. Less risk of hitting blood vessels or nerves, making it a safer site.
  • Rectus Femoris Muscle (Thigh): An alternative site that can be used in adults and children.
  • Dorsogluteal Site (Buttocks): Historically used, but not recommended currently due to the risk of damaging the sciatic nerve or blood vessels.

Selecting the correct injection site is crucial to ensure the safety and efficacy of the intramuscular injection, and the site can vary depending on specific patient needs and considerations.

Healthcare providers are trained to choose the most appropriate site based on various factors, including patient anatomy, age, and the type and amount of medication to be administered.

Intramuscular Injection Sites Vector Illustration

Signs of an Incorrect Intramuscular Injection

Incorrect intramuscular injections can present a myriad of signs and complications, depending on the severity and nature of the error.

Some common signs and symptoms include:

  • Pain and Discomfort: Persistent pain at the injection site beyond the usual post-injection soreness.
  • Swelling and Inflammation: Noticeable swelling, redness, and warmth at the injection site may indicate improper administration.
  • Abscess Formation: Formation of pus-filled lesions at the injection site can result from infections due to incorrect technique.
  • Nerve Damage: Tingling, numbness, or weakness may result from an injection that damages nerves, particularly with improper site selection.
  • Hematoma or Bleeding: If a blood vessel is punctured, it may lead to the formation of a hematoma or excessive bleeding.
  • Muscle Atrophy or Fibrosis: Repeated incorrect injections can lead to the wasting away of muscle tissue or the development of fibrous tissue.
  • Granuloma Formation: Small, knot-like formations of inflammatory cells may develop at the injection site due to reactions with the injected substance.
  • Inadequate Drug Response: If the medication does not reach the intended muscle, or if it is accidentally injected into subcutaneous tissue or a blood vessel, it may lead to suboptimal therapeutic effects.
  • Systemic Complications: Injecting into a blood vessel can also cause systemic complications depending on the medication, potentially affecting various organs.

Note: Detecting these signs early and seeking appropriate medical attention can help in managing the complications effectively and preventing any long-term adverse effects. The emphasis on proper training for healthcare providers in administering intramuscular injections is crucial in minimizing these risks.

How to Prevent Incorrect Intramuscular Injections?

Preventing incorrect intramuscular injections necessitates a multifaceted approach that involves strict adherence to established guidelines, continual education, and meticulous technique.

Here are several strategies to avoid errors in administering intramuscular injections:

  • Proper Training and Education: Healthcare providers should undergo rigorous training and regular refresher courses to stay updated on best practices and techniques.
  • Site Selection: Correctly identifying the suitable muscle and injection site is crucial. Selecting a site away from nerves and blood vessels minimizes the risk of damage.
  • Patient Assessment: Comprehensive assessment of the patient’s condition, muscle mass, and anatomy helps in choosing the appropriate injection site and technique.
  • Aseptic Technique: Maintaining sterility can prevent infections. This includes hand hygiene and use of sterile equipment.
  • Appropriate Needle Selection: Choosing the correct needle length and gauge according to the patient’s age, sex, weight, and muscle mass is vital to ensure the medication reaches the muscle layer.
  • Proper Injection Technique: Administering the injection at a 90-degree angle, and employing the Z-track method can prevent medication leakage into subcutaneous tissues.
  • Patient Positioning: Ensuring the patient is in a suitable position can help in exposing the injection site and relaxing the muscle, reducing the risk of complications.
  • Volume Consideration: Evaluating the volume of medication to be injected is essential, as excessive volumes may cause discomfort and complications.
  • Documentation: Keeping detailed records of injections, including site, medication, and dosage, helps in tracking and preventing repeated injections at the same site.
  • Monitoring and Follow-up: Close observation of the injection site for any adverse reactions and ensuring proper follow-up can aid in early detection and management of any complications.
  • Patient Education: Informing patients about potential reactions and instructing them to report any abnormalities can lead to early identification and intervention.

Note: By integrating these preventive measures, healthcare providers can significantly reduce the likelihood of incorrect intramuscular injections, thereby optimizing patient safety and therapeutic outcomes.

FAQs About Intramuscular Injections

What is the Most Common Cause of an Incorrect Intramuscular Injection?

The most common cause of an incorrect intramuscular injection is improper site selection, leading to the injection being administered too close to nerves, blood vessels, or bone.

This can occur due to inadequate training, lack of experience, or negligence in identifying the correct anatomical landmarks.

What are the Signs of an Incorrect Intramuscular Injection?

The signs of an incorrect intramuscular injection include:

  • Persistent pain and discomfort at the injection site
  • Swelling
  • Redness
  • Inflammation
  • Abscess formation
  • Nerve damage
  • Tingling, numbness, or weakness
  • Hematoma or bleeding
  • Muscle atrophy or fibrosis
  • Granuloma formation
  • Inadequate drug response
  • Potential systemic complications

What Should I Do if I Receive an Incorrect Intramuscular Injection?

If you suspect you have received an incorrect intramuscular injection, it’s essential to seek medical attention promptly to address any immediate complications.

Reporting any unusual signs, such as extreme pain, swelling, or changes in sensation, can help healthcare providers determine the appropriate intervention or treatment needed to mitigate adverse effects.

Proper documentation and follow-up are also crucial to monitor and manage any developing complications.

What are the Complications of an Incorrect Intramuscular Injection?

Incorrect intramuscular injections can lead to a range of complications, including localized infections, abscesses, tissue damage, and nerve damage.

These can result in prolonged pain, numbness, or loss of function in the affected area.

Systemic complications may also arise if the medication is inadvertently injected into a blood vessel, leading to adverse reactions affecting various organs.

Additionally, incorrect injections can result in suboptimal therapeutic effects, compromising the treatment’s efficacy.

Final Thoughts

Incorrect intramuscular injections, arising from varied causes such as inaccurate site selection, wrong needle selection, and improper technique, can result in serious complications, including infection, tissue damage, and suboptimal drug efficacy.

A thorough understanding of these underlying causes is crucial for healthcare providers to enhance the safety and effectiveness of intramuscular injection administration.

By adhering to established guidelines, receiving proper training, and maintaining a high level of vigilance, healthcare practitioners can substantially reduce the occurrence of incorrect intramuscular injections.

This is essential for optimizing patient outcomes and preserving the integrity of this indispensable medical procedure.

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


  • Polania Gutierrez JJ, Munakomi S. Intramuscular Injection. [Updated 2023 Aug 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.
  • Shah BS, Yarbrough C, Price A, Biswas R. An unfortunate injection. BMJ Case Rep. 2016.

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