How to Start an IV: A Step-by-Step Guide for Nurses
This post may contain affiliate links, which means I get a commission if you decide to purchase through my links, at no cost to you. Please read the affiliate disclosure for more information.
Learning how to start an IV is one of the core skills every nurse needs to own. Inpatient and ER nurses work with IVs constantly, inserting them, removing them, and running fluids or medications through them.
If you're new to nursing, this guide walks you through the whole process: when an IV is and isn't appropriate, how to pick the right gauge, what to gather, and a clean step-by-step for both insertion and removal, so you can start an IV with confidence.
When to Start an IV
The short answer is "when an IV is ordered." But part of thinking like a nurse is anticipating what's coming. As an ER nurse especially, you may see the patient before the provider and can place an IV when it's clearly indicated. On the inpatient side, most patients have some access (a peripheral IV, midline, PICC, or central line), and those peripheral IVs go bad often enough that you'll be replacing them regularly.
When NOT to Start an IV
There's no absolute contraindication to placing an IV, but certain factors rule out specific limbs or sites. Avoid extremities with:
Also Be Cautious With Numb Limbs
It's best to avoid limbs with significant motor or sensory deficits. If the arm is numb, the patient won't feel an infiltration, so a problem can go unnoticed until it's serious.
What IV Gauge Should You Use?
The gauge sets how big the catheter is. The bigger the IV, the faster fluid can run, but bigger also means more painful, harder to place, and a higher risk of phlebitis and vein irritation. Here's how the common sizes break down.
- Good for: infants
- Bad for: most adult scenarios — short, flimsy, won't last long
- Good for: peds, many med-surg adults, fragile "easily-blown" veins
- OK for: routine IV contrast, blood return
- Bad for: massive trauma, large-volume resuscitation, CT angiography
- Good for: most adult patients, CT angiography, fluid boluses, med infusions
- OK for: emergencies (codes, RRTs); often gives clean blood return for labs
- Bad for: massive trauma or large-volume resuscitation
- Good for: critical situations, rapid fluids or blood products, CTA, severe sepsis, burns, acute MI
- Bad for: small, fragile veins
- Good for: trauma and massive resuscitation
- Bad for: nearly everything else — unnecessary for most indications
Clinical Note: Bigger Isn't Always Better
Some nurses say to place the largest catheter the vein can hold, but that runs against good judgment. My friend Brian (@TheIVGuy) puts it well: choose your size based on the ordered therapy and anticipated needs. For most patients, a 20–22 gauge is the safest, most appropriate choice.
What Equipment Do You Need?
Before you start, gather your supplies. This becomes second nature fast, but it's worth memorizing as a new nurse.
How to Start an IV: Step by Step
Wash your hands and use universal precautions, including clean gloves, since you may contact blood. Have your site and catheter size already in mind.
Place the tourniquet proximal to your planned site. Look for straight, large veins, and palpate them: a good vein has bounce, and many that you can't see you can still feel.
Clean with a chlorhexidine (CHG) or alcohol swab and let it dry completely. With alcohol, start central and move outward in circles; with CHG, use a back-and-forth scrub. For deep veins, palpating with a gloved (not bare) finger is acceptable, and you should never tear off a glove fingertip; learn to palpate with gloves on.
While the site dries, open your flush and your extension loop or cap. If drawing blood, connect the blood transfer device to the dry loop or cap; otherwise prime the loop or cap with the flush and set it back in the clean kit. Open your IV, remove the needle cap, and twist the catheter to loosen it for cannulation.
With your non-dominant hand, pull the skin taut to anchor the vein, stop it rolling, and smooth the surface for insertion.
Set the needle against the skin at a 10–30 degree angle. The deeper the vein, the steeper your approach.
With the bevel up, puncture the skin and advance to the vein. You should see a flashback in the chamber or catheter (location varies by brand and size). Once you see it, drop the angle nearly parallel and advance the whole unit another 2–6 mm.
Now slide only the catheter forward off the needle and into the vein. Done right, it glides in without resistance. Dimpling of the skin usually means the tip is in the extravascular space.
Before retracting the needle, take off the tourniquet and apply digital pressure just beyond the catheter tip. Some 20–24g brands have a septum or blood-control feature that prevents backflow and skips the need for compression. Then press the activation button to retract the needle.
If labs are ordered, draw them now: connect your loop/cap with the blood transfer device to the IV hub and fill your tubes. If you're not drawing blood, connect the primed cap or loop instead. Then pulse-flush, confirm you can pull back blood return (reassurance the IV is well-seated), and finish flushing.
Secure with a securement device or tape and a transparent dressing like Tegaderm, keeping the insertion site visible. Tape down any extension loop so it can't snag and pull out. For a confused patient, wrap with Coban, leaving only the cap accessible. Then run your ordered fluids or meds, and you're done.
Clinical Note: "Digging"
If you don't get an initial flash, pull the needle and catheter back together almost to the skin (without exiting the epidermis), re-palpate, adjust your angle, and advance again. This is called "digging." Some patients don't tolerate it well, but it often takes only 2 or 3 attempts to succeed.
Never Re-Advance the Needle Into the Catheter
Once you've started sliding the catheter off the needle (step 6), do not push the needle back into the catheter to retry. The needle tip can shear off the plastic catheter and cause a catheter embolism. If that attempt fails, withdraw the whole unit together and start fresh with a new catheter.
How to Remove an IV
Knowing how to pull an IV matters too. When a patient is discharged or the IV has a complication, it comes out. Removal is simpler and can be done by a nurse or a patient care assistant.
Collect 2×2 gauze and tape or a bandaid.
Wash your hands and don clean gloves.
Hold the catheter in place while you peel off the Tegaderm and tape. Use an alcohol pad if it's very sticky or painful.
Place a 2×2 gauze over the site and pull the IV out in one smooth motion.
Hold pressure for 1–2 minutes until bleeding has stopped (longer if the patient is on anticoagulants).
Cover with gauze and tape or a bandaid.
Want to Master ECG Rhythms?
My video course ECG Rhythm Master is built specifically for nurses and goes far deeper into arrhythmias and emergency cardiac care.
- Identify every cardiac rhythm with confidence
- Understand the pathophysiology behind arrhythmias
- Manage rhythms like an expert nurse
- Master pacing, defibrillation, and synchronized cardioversion
Related Guides
References
- Intravenous Cannulation (Medscape).
- Peripheral Venous Access in Adults (UpToDate).
When do we take off the tourniquet?
Different nurses do this differently, but I’d say the best time to take off the tourniquet would be after extracting the needle when your catheter is in place. If you are drawing blood, sometimes leaving the tourniquet on will help you get blood, but will also increase the risk of hemolysis. Definitely make sure to take the tourniquet off before flushing as this could blow the vein.
I once had to have emergency dialysis due to AFR/AFI. Honestly the stent or whatever it was that was put into my femoral vein felt like a garden hose! I am average size. So does anyone else what gauge is used for Emergercy Dialysis?
That’s Nicely Explain about the IV Cannula.
ITS VERY INTERSTING ANS KNOWLEDGE ABLE FOR ALL
Love your content. Very helpful for our new grads. Just an FYI, under contraindications, you have bloot clots instead of blood. 🙂
Glad you like it!! I updated that btw – THANK YOU! 🙂