Ketorolac is not a muscle relaxer. It belongs to a class of medications called nonsteroidal anti-inflammatory drugs (NSAIDs), the same category as ibuprofen and naproxen. It works by blocking your body’s production of chemicals that cause pain, fever, and inflammation. While ketorolac is sometimes prescribed for conditions that involve muscle pain, it treats the pain and inflammation rather than relaxing the muscles themselves.
How Ketorolac Actually Works
Ketorolac reduces pain by inhibiting enzymes called cyclooxygenases, which your body uses to produce prostaglandins. Prostaglandins are chemicals that trigger inflammation, swelling, and pain signaling at the site of an injury. By cutting off that production, ketorolac reduces the inflammatory response and lowers the intensity of pain you feel.
This is fundamentally different from how muscle relaxants work. Muscle relaxants act on your nervous system, either in the brain and spinal cord or at the nerve-muscle connection itself, to reduce involuntary muscle contractions and spasms. Ketorolac has no direct effect on muscle tone or spasm. If your muscles are tight or in spasm, ketorolac won’t loosen them, but it can reduce the pain and inflammation surrounding the affected area.
Why Ketorolac Gets Confused With Muscle Relaxers
The confusion likely comes from the fact that ketorolac is a powerful pain reliever often given in situations where muscle pain is involved, like back injuries, post-surgical pain, or acute musculoskeletal injuries. It’s notably stronger than over-the-counter NSAIDs and is sometimes given as an injection in emergency rooms or after surgery, which can make it seem like a different type of drug entirely. But its strength doesn’t change its class. It’s still an anti-inflammatory painkiller, not a muscle relaxant.
When Ketorolac Is Used
Ketorolac is reserved for short-term management of moderately severe acute pain, the kind that would typically require opioid-level relief. It’s available as an injection (into a muscle or vein) and as oral tablets. The oral form is only used as a follow-up to the injectable version, not as a standalone prescription.
One of ketorolac’s most important restrictions is its duration limit. The FDA requires that total treatment not exceed five days across all forms combined. The risk of serious gastrointestinal complications, including stomach ulcers, bleeding, and perforation, increases with both higher doses and longer use. This makes ketorolac a short-term bridge for acute pain, not something you take on an ongoing basis.
Ketorolac Combined With Muscle Relaxants
For conditions like acute low back pain, doctors sometimes prescribe an NSAID and a muscle relaxant together. The logic is straightforward: pain triggers muscle spasms, which produce more inflammatory chemicals, which cause more pain. An NSAID targets the inflammation side of that cycle while a muscle relaxant addresses the spasm side.
A systematic review of six studies on acute low back pain found strong evidence that combining muscle relaxants with NSAIDs improved and accelerated recovery, though with a tradeoff of more drowsiness and dizziness from the muscle relaxant. However, a series of emergency department studies in the U.S. found that adding a muscle relaxant to an NSAID didn’t produce a meaningful difference in outcomes for people with acute, non-traumatic low back pain. The overall evidence for routinely combining the two remains mixed, though the combination is widely used in practice.
The key takeaway is that these are two separate drug classes doing two different jobs. If you’re dealing with muscle spasms alongside pain, ketorolac alone won’t address the spasm component.
Safety Concerns With Ketorolac
Because ketorolac is a potent NSAID, it carries the same category of risks as other drugs in its class, but at a heightened level due to its strength. The FDA’s prescribing label highlights three major areas of concern.
Gastrointestinal bleeding is the most prominent risk. Ketorolac can cause stomach ulcers, bleeding, or perforation at any point during use, sometimes without warning symptoms. The risk is higher if you smoke, drink alcohol, are over 65, take blood thinners, or have any history of stomach ulcers.
Kidney problems are another concern. Ketorolac is not appropriate for people with impaired kidney function or those at risk of dehydration. It can cause acute kidney injury, particularly in people who also take diuretics or blood pressure medications.
Cardiovascular risk also increases with NSAID use. Ketorolac can raise the chance of heart attack, stroke, or blood clots, and it may worsen existing high blood pressure or cause fluid retention. It’s specifically prohibited for pain management around coronary artery bypass surgery.
These risks are a major reason ketorolac is limited to five days. It’s an effective short-term painkiller, but it’s not designed for the kind of extended use that conditions like chronic muscle tension or ongoing back pain would require.