How to Start an IV Step by Step (With Printable Checklist)

Starting a peripheral intravenous (IV) line follows the same core sequence every time: gather supplies, select a vein, clean the skin, insert the catheter, confirm blood return, secure the site, and flush the line. Each step has details that can make the difference between a smooth, one-stick success and a painful do-over. Below is a walk-through of each phase, followed by a printable checklist you can tape to a supply cart or slip into a pocket.

Step-by-Step Printable Checklist

Print or screenshot this list and keep it handy during your next insertion. Each item is expanded in the sections that follow.

Verify the order: Confirm patient identity, check for allergies, and review the prescribed therapy to determine the right catheter gauge.
Gather supplies: IV catheter, extension set or saline lock, transparent dressing, skin antiseptic, tourniquet, gloves, tape, pre-filled saline flush syringe, sharps container.
Position the patient: Arm below heart level, supported on a flat surface. Ask the patient to make a fist or dangle the arm.
Apply the tourniquet: About 10 to 15 cm above your intended site. It should obstruct venous return without stopping the arterial pulse.
Select the vein: Palpate for a soft, bouncy, straight segment. Avoid areas over joints, bruised skin, or previously used veins.
Clean the site: Scrub with chlorhexidine-alcohol or alcohol for at least 30 seconds; let it dry completely.
Anchor and insert: Stretch the skin taut below the insertion point. Advance the needle bevel-up at a shallow angle (10 to 30 degrees). Watch for a flash of blood in the chamber.
Advance the catheter: Once you see flash, lower the angle and slide the plastic catheter forward off the needle. Release the tourniquet.
Dispose of the needle: Activate the safety mechanism and drop the needle into the sharps container immediately.
Connect and flush: Attach the extension set or saline lock. Flush with normal saline while watching for swelling or pain at the site.
Secure the site: Apply a transparent dressing over the insertion point. Loop and tape the tubing to prevent pulling.
Document: Record the catheter gauge, insertion site, number of attempts, date, time, and your name.

Choosing the Right Catheter Gauge

Catheter gauge matters more than most people realize. The gauge number runs backward: a lower number means a wider bore. A 14-gauge catheter is large enough for rapid trauma resuscitation, while a 24-gauge is thin enough for a fragile elderly patient or a neonate. For most routine IV fluids and medications, an 18- or 20-gauge catheter works well. If a patient needs a CT scan with contrast dye, blood products, or fast fluid boluses, reach for a 16- or 18-gauge. Larger catheters deliver considerably higher flow rates, which is critical when every second counts in a trauma bay or operating room.

Research confirms that increasing catheter diameter is one of the most effective ways to boost flow. In vitro testing showed that 14-gauge peripheral cannulas delivered flow rates well over double those of 14-gauge central venous catheters under the same conditions, largely because of the shorter catheter length.

¹ An 18-gauge peripheral IV can match the flow rate of a 14-gauge central line, and a 20-gauge peripheral IV outperforms a 16-gauge central line.² The practical lesson: don’t default to the biggest catheter you can find. Match the gauge to the therapy. Oversized catheters hurt more going in and can irritate the vein wall, while undersized ones slow down treatments that depend on speed.

One equipment detail worth noting: needle-free valve connectors, commonly used to reduce needlestick risk, can reduce flow through wider catheters by a substantial margin. In one study, flow through a 14-gauge cannula dropped by about a third when a needle-free valve was in line.¹ If rapid infusion is the goal, removing or bypassing the valve makes a real difference. Pressure bags also increase flow across all catheter sizes.

Picking the Best Vein

The ideal vein feels like a soft, bouncy tube under your fingertip. It sits in a straight segment, away from joints, and in an area free of bruises or prior punctures. The most popular sites are the veins on the back of the hand and the forearm, and both are reasonable choices depending on the situation.

A randomized trial of obstetric patients compared hand-dorsum placement with forearm placement and found first-attempt success rates of about 94% for the hand versus 87% for the forearm, though the difference narrowly missed conventional statistical significance.³ A separate systematic review of hospitalized adults found no significant difference between the two sites for complications like phlebitis or infiltration.⁴ In short, neither site is clearly superior across the board. The hand is often easier to palpate and visualize, while the forearm may be more comfortable for a patient who needs the IV for days and wants to use their hands freely.

The cephalic vein of the upper forearm deserves special mention. Research on vein diameter, flow velocity, and hemodilution capacity identified this vein as a strong candidate for longer-dwelling peripheral catheters, especially when the vein-to-catheter size ratio is at least three to one. Using the cephalic vein under these conditions may help reduce complications like chemical irritation and clot formation along the catheter.⁵

Skin Prep and Tourniquet Application

Cleaning the skin before needle insertion is not a formality. The antiseptic you choose and how long you scrub both affect infection risk. Chlorhexidine-alcohol solutions are preferred in most hospital protocols. A meta-analysis comparing chlorhexidine-alcohol with povidone-iodine for surgical skin preparation found that chlorhexidine-alcohol cut the rate of surgical site infection by roughly 40%.⁶ While those data come from surgical settings, the principle carries over to IV insertion: chlorhexidine-alcohol provides a broader antimicrobial effect and a longer residual effect on the skin. Apply it with friction, let it air-dry completely, and resist the urge to fan or blow on it.

For the tourniquet, tie it snugly enough to slow venous blood flow back to the heart while still allowing arterial blood to reach the hand. You should be able to feel a radial pulse with the tourniquet in place. A randomized trial comparing pressure-controlled tourniquets with standard elastic tourniquets found that maintaining a consistent pressure improved vein palpability from about 90% to nearly 99%, and reduced the time to catheter insertion by several seconds.⁷ Most clinicians use a flat elastic tourniquet and adjust by feel, but the takeaway is clear: a tourniquet that is too loose barely helps, and one that is too tight occludes the artery and makes the vein harder to find.

Other tricks to plump up veins include having the patient dangle their arm below heart level, applying a warm compress for a minute or two, and asking the patient to repeatedly open and close their fist. A study measuring vein diameter found that tourniquet application expanded the cubital vein by roughly a millimeter on average compared to baseline.⁸

The Insertion Itself

With the vein selected, the site prepped, and the tourniquet on, anchor the skin below your target point by pulling it taut with your non-dominant hand. This keeps the vein from rolling sideways when the needle touches it. Hold the catheter bevel-up at a shallow angle, roughly 10 to 30 degrees, and advance it steadily through the skin and into the vein. When the needle tip enters the vein lumen, you should see a flash of blood in the catheter’s flashback chamber.

That flash of blood is your confirmation. Once you see it, lower the catheter angle almost flat against the skin and advance the plastic catheter forward while holding the needle still. The catheter should slide smoothly off the needle and into the vein. Then release the tourniquet, apply gentle pressure over the vein above the catheter tip to prevent bleeding, remove the needle, and immediately activate the safety mechanism before dropping it in the sharps container.

Catheter design can influence your success rate. A comparative study tested three needle flashback designs: capillary, notched, and grooved. Nurses using the grooved needle flashback achieved catheter placement success rates about 20% higher than with notched designs and 22% higher than with capillary designs. Double punctures were most common with capillary flashback catheters.⁹ If your facility stocks more than one catheter brand, try the one with a grooved flashback; it may give you a better signal of when you are in the vein.

Securing and Dressing the Site

A well-secured IV line stays put. A poorly secured one dislodges, pulls partially out of the vein, and either infiltrates or needs replacement. The standard approach is a transparent semi-permeable dressing placed directly over the insertion point so you can inspect the site without removing anything. Loop the extension tubing and tape it to the skin a short distance away so that any tug on the line does not yank on the catheter.

Evidence on which specific dressing or securement device works best is surprisingly thin. A Cochrane systematic review examined the available trials and found very low-quality evidence across most comparisons. One small trial compared a bordered transparent dressing with simple tape and found higher catheter failure with the bordered dressing, though the certainty of that finding was very low. Rates of accidental dislodgement did not differ significantly between dressing types.¹⁰ The bottom line from that review is that no single dressing has proven decisively superior, so follow your facility’s protocol and focus on technique: keep the dressing dry, replace it when it loosens or gets soiled, and make sure nothing is pulling on the catheter hub.

Flushing and Maintaining the Line

Once the catheter is secured, flush it with a pre-filled syringe of normal saline. Push the saline slowly and watch the insertion site for any swelling, blanching, or pain, all of which suggest the catheter tip is not fully in the vein. A smooth, easy flush with no resistance and no patient discomfort confirms you have a patent line.

For intermittent-use IVs that sit idle between medication doses, periodic flushing keeps the catheter from clotting off. Normal saline is the standard flush for peripheral lines in adults, and research supports this practice. A systematic review found that heparin offered no clear advantage over saline for maintaining peripheral IV patency in adults and introduced additional safety concerns, including the risk of a dangerous drop in platelet count.¹¹ The picture is slightly different in pediatric and neonatal patients: a meta-analysis of randomized trials found that heparin flushes extended catheter dwell time and reduced complications in newborns.¹² For adult peripheral IVs, though, saline is simpler, cheaper, and just as effective.

When Should You Replace or Remove an IV

For years, the standard rule was to replace peripheral IVs every 72 to 96 hours, whether or not they were causing problems. That rule has been challenged by high-quality research. A Cochrane review pooling data from thousands of patients found no increase in catheter-related bloodstream infection, phlebitis, or mortality when IVs were replaced only for clinical reasons rather than on a fixed schedule.¹³ The clinically-indicated approach also saved about seven Australian dollars per catheter in direct costs and spared patients the pain of unnecessary re-sticks.¹⁴

Many hospitals have now shifted their policies accordingly. The practical rule: inspect the IV site at least every shift. If you see redness, swelling, streak marks, or pus, or if the patient reports pain at the site, remove the catheter. If none of those signs are present and the IV is functioning well, leave it alone. Remove the IV as soon as it is no longer needed for treatment; an idle catheter is just a risk without a benefit.

Making It Less Painful

Needle sticks hurt, and patients remember bad ones. There are two main pharmacological approaches to reducing insertion pain: topical anesthetic cream and vapocoolant spray. EMLA cream, a mix of lidocaine and prilocaine, works well but needs 30 to 60 minutes to fully numb the skin, making it impractical in emergency settings. Vapocoolant spray, which chills the skin for a few seconds immediately before the needle goes in, is faster and requires no wait time.

One study comparing the two found that vapocoolant spray produced significantly lower pain scores than EMLA cream during IV insertion in adults, with average pain ratings of about 1.3 versus 3.8 on a 10-point scale.¹⁵ A different trial in hemodialysis patients found that EMLA outperformed vapocoolant spray for total pain scores, though moderate-to-severe pain rates were similar between the two methods.¹⁶ Results vary by setting and patient population, but the key point is that both options work better than nothing.

For children, distraction techniques can be just as powerful as numbing agents. A randomized trial found that virtual reality distraction during IV insertion significantly reduced pain and anxiety in pediatric patients.¹⁷ Even without VR goggles, simple measures like asking a child to blow bubbles, count backward, or watch a video on a phone can redirect their attention away from the needle.

Vasovagal reactions, that light-headed, clammy feeling that can escalate to fainting, are another comfort concern. A small trial in pediatric and young adult patients tested a leg-crossing and muscle-tensing technique and found that only 15% of the intervention group experienced vasovagal symptoms, compared with over 60% of the control group.¹⁸ If your patient tells you they tend to faint during blood draws or needle sticks, have them cross their legs and tense their thigh and abdominal muscles during the insertion. It is free, it takes no extra time, and the evidence suggests it works.

Difficult Vein Access

Some patients are genuinely hard sticks: people with obesity, chronic illness, dark skin, edema, a history of IV drug use, or veins scarred by repeated chemotherapy. When two attempts by an experienced clinician fail, it is time to reach for ultrasound.

Ultrasound-guided peripheral IV insertion has become standard practice in emergency departments and ICUs for difficult-access patients. A meta-analysis found that ultrasound more than doubled the odds of successful cannulation in patients who had already failed traditional attempts.¹⁹ A second systematic review reported even stronger results, with ultrasound nearly quadrupling success odds compared to landmark-based techniques.²⁰ Beyond success rates, ultrasound guidance is associated with longer catheter dwell times, fewer repeat procedures, and fewer escalations to central line placement.²¹

One caveat: vein-finding gadgets that use near-infrared light to project vein maps onto the skin look impressive, but the evidence for their effectiveness is underwhelming. A randomized trial in oncology patients found no significant difference in pain, fear, or insertion success between standard palpation and a vein visualization device.²² These devices can help you see where veins are, but seeing a vein and successfully threading a catheter into it are not the same skill. Ultrasound gives you real-time depth information and shows you the needle entering the vein, which is why it is the tool of choice for genuinely difficult access.

Complications to Recognize Early

Most peripheral IV complications are minor, but catching them early prevents real harm. The main ones to watch for:

Infiltration: Fluid leaks into the tissue around the vein instead of flowing through it. You will see swelling, cool pale skin, and the patient may feel tightness or a dull ache. Stop the infusion and remove the catheter.
Extravasation: The same leakage, but with a caustic or cytotoxic drug. This is a medical emergency because certain medications can cause tissue death and long-term damage if they escape the vein.²³
Phlebitis: Inflammation of the vein, marked by redness, warmth, and tenderness along the vein’s path. Risk factors include catheter placement in veins on the back of the hand, infusion of certain irritating drugs, and prolonged immobility.²⁴
Occlusion: The catheter clogs with a blood clot or medication precipitate. You will feel resistance when you try to flush. Try repositioning the patient’s arm first; if that does not help, remove the catheter.
Hematoma: Blood pools under the skin during or after insertion, leaving a bruise. This usually happens when the needle goes through both walls of the vein or the tourniquet is released too late.

Paying attention to patient complaints is one of the best early-warning systems. Phlebitis research specifically highlights that taking pain reports seriously and acting on them can prevent complications from worsening. If a patient says something feels wrong at the IV site, believe them and check.

Protecting Yourself from Needlestick Injuries

Every IV start puts you within inches of a contaminated sharp. Needlestick injuries carry the risk of transmitting bloodborne pathogens, and they happen far more often than most clinicians like to admit. Safety-engineered catheter devices, which retract or shield the needle after withdrawal, dramatically reduce this risk. A study across multiple hospitals found that the needlestick injury rate with conventional catheters was roughly 12 times higher than with safety-engineered devices.²⁵

Use the safety mechanism the instant you withdraw the needle from the catheter, before you do anything else. Don’t set the needle down on the bed or tuck it between your fingers while you connect the extension set. Have your sharps container within arm’s reach. These habits sound obvious, but most needlestick injuries happen during exactly those few seconds between needle withdrawal and disposal, when attention shifts to the next task. The patient needs a functioning IV, but you need to go home without an occupational exposure.