A common (>10%) side effect is drowsiness. Infrequent (<1%) side effects include paresthesia, prolonged bleeding time, injection site pain, purpura, sweating, abnormal thinking, increased production of tears, edema, pallor, dry mouth, abnormal taste, urinary frequency, increased liver enzymes, itching and others. Platelet function can be decreased by use of ketorolac.
Though uncommon, potentially fatal adverse effects include stroke, myocardial infarction, GI bleeding, Stevens-Johnson Syndrome, toxic epidermal necrolysis and anaphylaxis. In terms of safety, ketorolac has been assessed to be a relatively higher-risk NSAID when compared to aceclofenac, celecoxib, and ibuprofen.
Ketorolac can interact with other medications. Probenecid can increase the probability of having an adverse reaction when taken with ketorolac. Pentoxifylline can increase the risk of bleeding. When aspirin is taken at the same time as ketorolac, the effectiveness is decreased. Problematic GI effects are additive and become more likely if potassium supplements, aspirin, other NSAIDs, corticosteroids, or alcohol is taken at the same time. The effectiveness of antihypertensives and diuretics can be lowered. The use of ketorolac can increase serum lithium levels to the point of toxicity. Toxicity to methotrexate is more likely if ketorolac is taken at the same time. The risk of bleeding increases with the concurrent medications clopidogrel, cefoperazone, valproic acid, cefotetan, eptifibatide, tirofiban, and ticlopidine. Anticoagulants and thrombolytic medications also increase the likelihood of bleeding. Medications used to treat cancer can interact with ketorolac along with radiation therapy. The risk of toxicity to the kidneys increases when ketorolac is taken with cyclosporine.
Interactions with ketorolac also exist with some herbal supplements. The use of Panax ginseng, clove, ginger, arnica, feverfew, dong quai, chamomile, and Ginkgo biloba increases the risk of bleeding.
Mechanism of action
The primary mechanism of action responsible for ketorolac’s anti-inflammatory, antipyretic and analgesic effects is the inhibition of prostaglandin synthesis by competitive blocking of the enzyme cyclooxygenase (COX). Ketorolac is a non-selective COX inhibitor. It is considered a first-generation NSAID.