Ultracet is a yellow orange coated pill with OM on one side. It's a pill for pain relief, with tramadol and acetaminophen. Tramadol is similarly classed in opiate type pain relievers like Vicodin. Acetaminophen is typically known as Tylenol. The only other pill with OM is likely blue or green in color, for birth control, Ortho Tri Cyclen.