Arterial catheterization is not without its risks. For example, there is the initial pain when the needle stick is first used to place the catheter in the artery. Doctors usually use an anesthetic to numb the area before inserting the needle, and the discomfort lessens once the catheter has been in place for some time.

There is a risk of infection. Bacteria can travel up the catheter from the skin (or anything else the catheter comes in contact with) and into the bloodstream. The longer the catheter stays in the body, the higher the risk of infection. This risk is minimized by taking special care in bandaging the skin at the site of the catheter and changing the tubing regularly.

Blood clots can form at the tips of the arterial catheters, blocking blood flow. If there is no other blood vessel to carry blood to the area beyond the clot, the patient may lose a limb. However this happens very rarely and ICU staff regularly checks for bloodflow in the limbs to make sure there are no clots blocking it.

Finally, there is a risk that the wound will continue to bleed even after the catheter is inserted. In that case the hospital will put continuous pressure on the catheter site until the bleeding stops.