Painkillers, known medically as analgesics, are drugs that reduce or block pain. They range from over-the-counter tablets you can buy at any pharmacy to powerful prescription medications reserved for severe or chronic conditions. The two broadest categories are nonopioid analgesics (like ibuprofen and acetaminophen) and opioid analgesics (like morphine and oxycodone), but several other drug classes also treat pain through entirely different mechanisms.
Over-the-Counter Options: NSAIDs and Acetaminophen
For mild to moderate pain, most people reach for one of two types of medication: NSAIDs or acetaminophen. Both are available without a prescription and reduce fever in addition to pain, but they work in different ways and carry different risks.
NSAIDs, which include ibuprofen, aspirin, and naproxen, block enzymes called COX-1 and COX-2. These enzymes normally produce prostaglandins, chemicals that trigger inflammation, swelling, and pain at the site of an injury. By reducing prostaglandin production throughout the body, NSAIDs tackle both pain and the inflammation behind it. That makes them especially useful for conditions like sprains, arthritis, menstrual cramps, and headaches where inflammation plays a role.
Acetaminophen (sold as Tylenol in the U.S. and paracetamol elsewhere) also appears to inhibit COX enzymes, but only within the central nervous system. It doesn’t reduce inflammation in your joints or muscles the way NSAIDs do. Instead, it raises your pain threshold so that a given level of pain registers less intensely. It also acts on the heat-regulating area of the brain to bring down a fever. Because it skips the anti-inflammatory effect, acetaminophen is a better choice when inflammation isn’t the main issue, or when you need to avoid the stomach and cardiovascular risks that come with NSAIDs.
Risks of Common Over-the-Counter Painkillers
Neither NSAIDs nor acetaminophen is risk-free, particularly with regular use. Endoscopic studies show that 20 to 30 percent of chronic NSAID users develop stomach ulcers, and serious complications like bleeding or perforation occur at a rate of roughly 2 percent per year in average-risk users, climbing to 10 percent per year in high-risk patients. Long-term NSAID use has also been linked to increased cardiovascular risk. Research on ibuprofen, diclofenac, and certain COX-2 selective inhibitors has found elevated rates of heart attack with ongoing use.
Acetaminophen is gentler on the stomach and heart, but the liver is its weak point. The FDA sets the maximum adult dose at 4,000 milligrams per day across all products you’re taking. That ceiling matters because acetaminophen hides in hundreds of combination products (cold medicines, sleep aids, prescription pain pills), and it’s easy to exceed a safe dose without realizing it. Overdose can cause severe liver damage.
Topical Painkillers
When pain is localized to one area, topical versions of the same drugs can be surprisingly effective. Topical NSAID gels and patches (like diclofenac gel) deliver the drug directly to the painful tissue while producing only 2 to 8 percent of the peak blood levels you’d get from swallowing a pill. Systematic reviews have found comparable pain relief between topical and oral NSAIDs for conditions like knee osteoarthritis, with a much lower risk of stomach and cardiovascular side effects.
Lidocaine patches and creams numb a specific area by blocking nerve signals at the skin’s surface. They’re commonly used for nerve pain conditions like shingles-related pain. Systemic absorption is low under normal use, though applying them to damaged or inflamed skin increases absorption and risk.
Opioid Painkillers
For severe pain that doesn’t respond to over-the-counter options, opioids are the most powerful class of painkiller available. This group includes codeine and tramadol at the milder end, and morphine, oxycodone, fentanyl, and hydromorphone at the stronger end. They work by binding to opioid receptors in the brain and spinal cord, which reduces the release of chemical messengers involved in transmitting pain signals. The result is a dampening of pain perception at its source in the nervous system.
The World Health Organization organizes pain treatment in a three-step ladder. Step one (mild pain) calls for NSAIDs or acetaminophen. Step two (moderate pain) adds weaker opioids like codeine or tramadol. Step three (severe, persistent pain) uses potent opioids like morphine or fentanyl, often alongside nonopioid painkillers for added effect.
Opioid Side Effects and the Dependence Question
Opioids affect far more than just pain. The most common side effects are constipation and nausea, both of which are persistent problems. Unlike many side effects, the body often does not develop tolerance to constipation, meaning it doesn’t go away with continued use. Other side effects include sedation, dizziness, vomiting, and respiratory depression, which is the slowing of breathing that makes overdose potentially fatal.
There’s an important distinction between physical dependence and addiction. Nearly everyone who takes opioids for months or longer will develop physical dependence, meaning their body adapts to the drug and they’ll experience withdrawal symptoms if they stop suddenly. This is a normal biological response, similar to what happens when people discontinue certain antidepressants or blood pressure medications. Addiction is something different: it involves intense cravings, loss of control over use, and continued use despite harmful consequences. Research suggests that only around 8 percent or fewer of patients on long-term opioid therapy for pain develop addiction. Dependence is expected. Addiction is not inevitable, but the risk is real enough that opioids are generally prescribed cautiously and for the shortest effective duration.
Painkillers for Nerve Pain
Standard painkillers often don’t work well for nerve pain, the burning, shooting, or tingling sensations caused by damaged nerves. Conditions like diabetic neuropathy, sciatica, and pain after shingles frequently require a different approach altogether.
Two classes of medication originally designed for other conditions have become first-line treatments for nerve pain. Certain antidepressants, particularly those that boost both serotonin and norepinephrine activity in the brain, strengthen the body’s own pain-dampening pathways. Antiseizure medications like gabapentin and pregabalin work by calming overactive nerve signaling, targeting the calcium and sodium channels that fire excessively in damaged nerves. Neither of these classes is a traditional “painkiller” in the way most people think of the term, but for nerve pain specifically, they often outperform NSAIDs and even opioids.
A New Class of Non-Opioid Painkiller
The FDA recently approved suzetrigine (brand name Journavx), the first in a new class of pain medications that targets sodium channels in the peripheral nervous system. It blocks pain signals before they ever reach the brain, but through a completely different mechanism than opioids. It carries no risk of the respiratory depression, dependence, or euphoria associated with opioid drugs. In clinical trials, it was tested against placebo and active comparators in patients recovering from abdominal surgery and bunion removal, and it is approved for moderate to severe acute pain in adults. Its arrival marks the first genuinely new mechanism for treating acute pain in decades.
How Painkillers Are Matched to Pain
Choosing the right painkiller depends on the type of pain, its severity, and how long it’s expected to last. A sprained ankle responds well to an NSAID because inflammation is driving the pain. A tension headache may call for acetaminophen. Post-surgical pain might start with an opioid and transition to over-the-counter options as healing progresses. Chronic nerve pain from diabetes is best managed with antiseizure or antidepressant medications rather than pills designed for inflammation or acute injury.
Combining different types of painkillers often works better than increasing the dose of a single one. Taking acetaminophen alongside an NSAID, for example, targets pain through two separate pathways simultaneously. In surgical settings, adding nonopioid painkillers can reduce the amount of opioid needed, which lowers the risk of side effects like nausea and excessive sedation. This layered approach is the foundation of modern pain management.