Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Clinical Nursing Skills

12.2 Administering Parenteral Medications

Clinical Nursing Skills12.2 Administering Parenteral Medications

Learning Objectives

By the end of this section, you will be able to:

  • Describe the different parenteral routes of medication administration
  • Identify safety guidelines for parenteral medication administration
  • Recognize equipment used for parenteral medication administration

Parenteral medication administration refers to injecting medications directly into the tissues and circulatory system bypassing the skin, mucous membranes, and gastrointestinal tract. Administering medications via the parenteral route may be useful when the medication is poorly absorbed orally, when immediate onset or delayed onset is required, or if the patient is unable to tolerate oral administration of medications. Medications administered via this route are injected into the body; therefore, it is critical to ensure proper technique is followed at all times. Nurses must demonstrate competency before administering medications via this route because incorrect technique may cause physical harm to the patient and adversely affect medication absorption. This section will describe the various parenteral routes for medication administration and identify guidelines to prepare you to administer medications via this route safely, including the necessary equipment.

Types of Parenteral Routes

Medications administered via the parenteral route bypass the gastrointestinal system, eliminating the effects of first-pass metabolism. Compared to oral administration, medications administered via the parenteral route have a faster onset and provide stronger effects because they are not digested in the gastrointestinal tract. The parenteral route for medication administration is used when a rapid effect of the drug is required, a precise serum medication level is required, or when medications are poorly absorbed by the gastrointestinal route. Additionally, the parenteral route may be the best option for patients experiencing nausea and vomiting; those unable to tolerate oral fluids; those unable to swallow; and those taking medications that are known to irritate the gastrointestinal system. Common routes of parenteral medication administration include intramuscular, subcutaneous, intravenous, and intradermal (Figure 12.10).

Diagram showing angle of injections for parenteral administration: intramuscular (ninety degrees), subcutaneous (forty-five degrees), intravenous (twenty-five degrees), intradermal (ten to fifteen degrees)
Figure 12.10 The type of parenteral administration determines the depth of the insertion and the angle of needle insertion. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)


Medications administered via the intramuscular (IM) route are injected directly into a muscle. The intramuscular route is preferred to the subcutaneous route when larger volumes of medication need to be administered. The speed of absorption into the bloodstream depends on the blood supply to the muscle. Sites with more blood supply provide faster absorption. Examples of medications administered via the intramuscular route include antibiotics, biologicals, and hormonal agents.


The subcutaneous (SQ) route injects the medication into the adipose tissue, the loose connective tissue directly under the dermis. The medication is gradually distributed into the circulation system through the capillaries. Medications injected subcutaneously are absorbed slowly because fewer vessels are present in subcutaneous tissue. Examples of medications administered via the subcutaneous route include insulin, heparin, and epinephrine.


The intravenous (IV) route injects the medication directly into a vein through an IV line. These medications may be administered as a single dose or continuous infusion. Medications administered via this route are directly introduced into the bloodstream, which eliminates the need for first-pass metabolism. Medications administered via the IV route have 100% bioavailability, the extent and rate at which a drug is absorbed and becomes available to the systemic circulation, and a rapid effect. As such, patients must be closely monitored to ensure the medication has the desired effect and to identify any undesired side effects. The effects of medications administered via this route tend to last a shorter time than other routes; therefore, some medications may need to be administered via a continuous infusion to maintain lasting effects.

The IV route is the preferred route to deliver a precise dose quickly or when the medication would be irritating to the body when administered via another parenteral route. If a patient already has an IV infusing, the nurse must ensure the medication to be administered is available in IV form and is compatible with other IV medications being given. Generally, healthcare providers attempt to use an already established route to administer a medication versus causing the patient unnecessary pain or discomfort. For example, administering a medication via an established IV causes less pain than administering additional IM or SQ injections. Examples of medications administered via the IV route include antibiotics, antihypertensives, opioids, and fluids. Intravenous medication administration will be further discussed in Chapter 13 Intravenous Administration.


When administering medications via the intradermal (ID) route, the medication is injected into the dermis, just below the epidermis. Medications administered via this route are absorbed slowly because of the limited blood supply found within the top layers of skin. Therefore, ID injections have very little systemic effect, making them ideal when a local effect is warranted. Examples of medications administered via the ID route include tuberculosis tests, local anesthetics, and allergy tests.

Other Parenteral Routes

Although intramuscular, subcutaneous, intravenous, and intradermal are the most common parenteral routes, there are additional parenteral routes. For example, parenteral medications may also be administered via the intra-arterial, intracardiac, intraperitoneal, intraosseous, and intrathecal routes. Each of these routes is unique, used under certain circumstances, and requires specialized training.

The intra-arterial route injects the medication into an artery rather than a vein. The carotid or vertebral arteries are the most common sites. Advantages of this route are that absorption is fast, within about fifteen to thirty seconds, and it allows for 100 percent bioavailability of the medication. This route may be used to inject contrast after an arterial puncture for angiography, to administer regional chemotherapy, as well as to treat malignant brain tumors. However, it is rarely used because of the high risk of patient injury during manipulation. As such, healthcare agencies must have strict protocols in place that are aligned with the state-specific Nurse Practice Act that dictate who, when, and how arterial lines are inserted, used, and maintained.

The intracardiac route injects medications directly into the myocardium or into one of the cardiac chambers. This route is fairly simple, easy to use, and inexpensive; however, it may not be an effective route for those with coronary stenosis or ischemic heart diseases. The primary indication for the intracardiac route is administration of resuscitative medications when other medication routes have failed during a cardiac arrest.

The intraperitoneal route injects medications into the lower left or right quadrants of the abdomen and into the peritoneal cavity. A benefit of this route is that the peritoneal cavity can absorb large amounts of medications quickly, while disadvantages include variability in effectiveness and potential for misinjection. This route is most commonly indicated for the treatment of peritoneal cancers.

The intraosseous route injects medications through a hollow-bore needle placed through the cortex of a bone into the medullary space. Intraosseous access is relatively fast and easy to obtain. Although this route can be extremely painful for the patient, it may be particularly useful in emergency situations, in neonates when peripheral and central venous accesses have not been successful, as well as for administering prophylactic antibiotics for regional surgeries.

The intrathecal route injects the medication into the subarachnoid space around the spinal cord. The intrathecal route is not to be confused with the epidural route, which injects medication into the epidural space and provides localized pain relief instead of the more profound effect achieved by the intrathecal route. After an anesthetic is injected, a needle is inserted into the lower spine between two vertebrae, where the medication is then injected in the subarachnoid space that is filled with cerebrospinal fluid. This route may be used with opioids for pain that cannot be controlled via alternative routes, for hospice patients, and for chronic cancer-related pain.

Safety Guidelines for Parenteral Medication Administration

When administering medications via the parenteral route, safety is of the utmost importance. Medications administered parenterally are rapidly absorbed; therefore, there is an increased risk of overdose and rapid development of life-threatening adverse reactions. Furthermore, the speed of absorption may make it difficult to reverse the physiological effects of the drug. For this reason, it is critical to check the rights of medication administration before administering any medications to ensure the right dose, of the right medication, to the right patient, via the right route, and at the right time. This includes confirming the medication order; the patient’s identity, allergies, and contraindications; medication calculations; necessary assessments; expiration dates; and safety precautions for high-alert medications, as well as questioning orders that do not seem correct.

The parenteral route requires the skin to be broken; therefore, the risk of infection is increased. To reduce the risk of infection, it is critical to abide by safe injection practices. For example, hand hygiene should always be performed before preparing medications, administering medications, and after removing gloves or touching the patient. Careful consideration must be given to ensure the needle is kept sterile. This includes ensuring the needle does not touch unsterile surfaces, such as the outside of the vial or counter, and ensuring the needle is covered when not in use. Care must also be given to avoid contaminating the length of the plunger and the Luer-lock, if using a two-piece needle and syringe, because contamination of these parts has the potential to introduce contaminants into the syringe (Figure 12.11).

A labeled illustration of a syringe with needle, needle hub, and plunger is shown. The label reads "keep sterile."
Figure 12.11 Maintaining the sterility of the syringe and needle is crucial to prevent contamination and ensure safe medical procedures. The needle, needle hub, tip of syringe barrel, and shaft of the plunger must remain sterile at all times. (credit: modification of “Needle syringe” by Togo picture gallery/Wikimedia Commons, CC BY 3.0)

It is also imperative to adequately prepare the patient’s skin for the injection. Soap and water should be used when the skin is soiled, followed by cleansing the skin with an alcohol swab. To accurately cleanse the skin with an alcohol swab, use a circular motion to rub the area, from the center of the site outward in a 2 in (5 cm) radius, for fifteen seconds and then allow the area to dry for thirty seconds. Consideration should also be given to the location of the injection, the size of the needle, proper positioning of the patient, and insertion of the needle at an appropriate angle and depth.

Care should also be given to prevent needlestick injuries. When possible, needles should not be recapped. Alternatives to recapping may be to engage the safety device, change needles between preparing and administering the medication, or use a needleless system. The needle safety device should be engaged immediately after the injection (Figure 12.12), using a hard surface to engage the safety instead of your finger. The needle should be disposed of in the sharps box. In the event of a needlestick injury, the injury should be reported immediately, and next steps should be determined according to the agency’s policy. Strategies should then be identified to determine how the injury may be prevented in the future. To reduce the incidence of needlestick injuries, nurses should practice using the safety device on any new syringe being introduced to the facility. Every safety device is different and therefore requires familiarity before use on patients.

A photograph of a syringe held between thumb and forefinger.
Figure 12.12 The nurse engages the needle safety device to prevent accidental needlestick injuries. (credit: modification of “Sept-22-2015-040.jpg” by British Columbia Institute of Technology, CC BY 4.0.)

Clinical Safety and Procedures (QSEN)

QSEN Competency: Safety: Parenteral Medication Administration

Disclaimer: Always follow the agency’s policy for medication administration.

Definition: Reduce the risk of harm to patients through effective, efficient, and competent performance.

Knowledge: The nurse will analyze basic safety principles, understand evidence-based practice standards, and reflect on unsafe nursing practices.

Skill: Demonstrate effective strategies to reduce the risk of harm. The nurse will:

  • Avoid distractions and minimize disruptions when administering medications.
  • Ensure all medication rights have been confirmed at least three times.
  • Compare the medication order to the MAR.
  • Check for allergies.
  • Confirm medication calculations.
  • Check expiration dates.
  • Perform hand hygiene.
  • Prevent needle/syringe contamination.
  • Prevent medication solution contamination.
  • Educate the patient.
  • Clean the site.
  • Use the correct needle size.
  • Use correct administration rate.
  • Prevent accidental needlesticks.
  • Report all medication errors, adverse reactions, or near misses.

Attitude: The nurse will accept their individual role in preventing errors by adhering to safe, evidence-based practice standards.

Compatibility of Medications

When administering multiple parenteral medications at once, it is important to assess the compatibility of the medications. The compatibility of medications is the capability of administering two or more medications together without the two medications interacting with one another. When checking for compatibility of medications, you are checking to ensure there are no drug-drug interactions that would change the chemical makeup or effects of either drug. When medication incompatibilities occur, they can cause reduced effects of the medications or make them inactive, form harmful chemical reactions, increase toxicity of the medications, or create microparticles that are then injected into the body. To assess medication compatibility, the medications may be entered into an electronic drug interaction database or looked up in a drug reference guide. Often, organizations will provide a compatibility chart for quick access to commonly used medications. If in doubt, consult the pharmacy for further assistance.

Equipment Used for Parenteral Medication Administration

Equipment, such as syringes, needles, and needleless systems are required to administer medications via the parenteral route. Syringes and needles come in a variety of sizes. Selecting the most appropriate syringe and needle size depends on several factors, including the type of medication, location of injection, amount of medication required, and the size of the patient. As an alternative, needleless systems may be an option in some circumstances.


A syringe is a sterile device that consists of a calibrated cylinder-shaped barrel with a sliding plunger at one end and an open tip that attaches to a needle or needleless system at the other end (Figure 12.13). Syringes come in a variety of sizes, ranging from 0.5 mL to 60 mL. The amount of the medication to be administered will determine the size of the syringe to use. Syringes come prepared as sterile devices from the manufacturer. After the package containing the syringe is opened, hold the syringe by the barrel to preserve sterility. Ensure that both the tip and the plunger remain sterile to prevent contamination.

An illustration shows a syringe with labels showing plunger, flange, barrel, plunger tip, volume markings, needle adapter, needle hub, shaft of needle, bevel, and protective cover.
Figure 12.13 Syringes are used to administer parenteral medications. (credit: modification of “Labelled syringe” by Glynda Rees Doyle and Jodie Anita McCutcheon/British Columbia Institute of Technology, CC BY 4.0.)

Syringes may either be Luer-lock or Luer-slip (Figure 12.14). A Luer-lock connection allows the needle to be twisted on the tip of the syringe to lock the needle in place, whereas a Luer-slip, sometimes referred to as non-Luer-lock, connector fits the needle firmly on the tip of the syringe using friction but does not twist to lock it in place. Some syringes come packaged with a sterile needle, such as insulin and tuberculin syringes, with the needle built into the syringe. Other syringes may be packaged without a needle.

Syringes with (a) Luer-Lock needle connection and (b) Luer-Slip needle connection
Figure 12.14 (a) Syringes can be connected to a needle using one of two methods. A Luer-lock connection allows the needle to screw onto the syringe. (b) A Luer-slip connection allows a needle to remain in place using friction. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)


A needle is a hollow metal tube with a sharp and slanted point, called a bevel, and a hub that attaches the needle to the syringe (Figure 12.15). They are considered to be sterile and should remain sterile at all times. Needles come in various gauges and lengths. The needle gauge (G) measures the width or diameter of the needle. Typically, needles intended for parenteral medication administration range from 18G to 31G. The bigger the gauge, the smaller the needle. Needles also come in a variety of lengths, with typical lengths for parenteral injections ranging from 3/8 to 1.5 in (9.5 to 38 mm). Different-sized needles are used for different purposes.

An illustration shows the parts of a needle labeled: Needle cap, bevel, lumen, shaft, hub.
Figure 12.15 Needles are composed of a hub, needle shaft, lumen, bevel, and needle cap. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Determining Needle Size

Determining the correct needle size is important to ensure the appropriate delivery of the medication into the correct site. Furthermore, using the correct needle size also may reduce the risk of complications, such as pain, bruising, and abscesses. When selecting the correct needle size, the gauge and needle length need to be determined using a resource like a needle gauge chart (Figure 12.16). To determine the correct needle size, consideration should be given to factors such as injection site, the size of the patient, body composition, and the amount of medication being administered.

Chart showing appropriate needle gauge and length, with examples, and injection site, for various age groups
Figure 12.16 Needles come in a variety of gauges and lengths. Nurses are responsible for determining the correct needle length and gauge depending on the patient, medication, location and depth of injection required, and the viscosity of the medication. This chart is only an example of a resource a nurse might use, and the needle sizes in it are not necessarily to scale. (credit: modification of “You Call the Shots” by CDC, Public Domain)

The gauge of a needle is the diameter of the hole in the needle. When selecting the gauge of the needle, it is important to consider the thickness of the skin and the depth of the injection. Larger-gauged needles have thicker needle walls; therefore, they are stronger and more suitable for intramuscular injections. Keep in mind that a larger gauge is a smaller number. On the other hand, smaller-gauged needles, or higher numbers, tend to create less pain and bruising for the patient and are most suitable for ID and SQ injections. Consideration should also be given to the viscosity of the fluid; higher-viscosity medications require lower-gauge needles. The most common needle gauge used for ID and SQ injections is 27G, whereas 25G needles are more commonly used for IM injections.

When selecting the length of the needle, it is important to consider the location of the injection. For example, longer needles may be used for IM injections, whereas shorter needles would be used for ID and SQ injections. The most common needle length for both ID and SQ injections is 0.5 in (13 mm), whereas 1 in (25 mm) and 1.25 in (32 mm) needles are commonly used for intramuscular injections. Patients who are very thin or exhibit cachexia, weakness, and wasting of the body as a result of severe chronic illness may require shorter needles based on assessment of the individual’s anatomy.

Needleless Systems

A needleless system allows parenteral medications to be administered without the use of a needle. These systems alleviate the potential for needlestick injuries, cross contamination, and reuse of needles as well as reduce the pain experienced by the patient. There are needleless injectors (Figure 12.17), also known as jet injectors, which deliver a spring-powered injection that penetrates the skin without using a needle. Jet injectors may be used to administer medications via the subcutaneous or intramuscular routes.

A photograph shows a jet injector.
Figure 12.17 A needleless injector, also known as a jet injector or needle-free injection system, is a medical device that delivers medication or vaccines through the skin using a high-pressure mechanism. (credit: modification of “Insulin Delivery Devices” by “BruceBlaus”/Wikimedia Commons, CC BY 4.0.)

Needle-free valves may be connected to IV catheters or administration sets to provide safe administration of IV medications. When used, the Luer-lock end of the needle-free valve may be cleansed with an agency-approved substance, and then a Luer-lock syringe may be twisted onto the valve. When the syringe or set is attached, a mechanism within the valve opens, allowing fluids to flow into or out of the IV line. When the syringe or set is removed, the valve automatically closes, helping to maintain the sterility of the IV system.


This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at
Citation information

© Jun 25, 2024 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.