Pain expert Dr. Scott Fishman answers questions about pain medication:

Q: Why do so many narcotic medications contain caffeine, acetaminophen, or ibuprofen?

A: Opioids are often combined with other analgesics, namely aspirin, ibuprofen, or acetaminophen, in order to boost and extend their power. Usually the opioids that contain these extra boosters are short-acting drugs, and without them their punch would fade faster. Furthermore, the analgesic increases the potency of the opioid, consequently the dose can be smaller.

Most commonly prescribed pain medications contain an opioid and a booster. Percocet is a combination of acetaminophen (Tylenol) and the narcotic oxycodone and it works for three to four hours. Other combination drugs include Darvocet (the opioid propoxyphene and acetaminophen), Darvon (the opioid propoxyphene, aspirin and caffeine), Percodan (the opioid oxycodone and aspirin), Tylenol #1 through Tylenol #4 (acetaminophen and the opioid codeine), and Vicodin (the opioid hydrocodone and acetaminophen).

While combining ingredients enhances the power and duration of these drugs, they can be problematic if used for long periods of time or in excessive dosages. They are best used for short-term, acute pain, not chronic pain that lasts for months and years. Counter to what most people believe, the side effects of drugs like acetaminophen or aspirin can be as lethal as the side effects of the opioid narcotic.