What are the benefits of painkillers? The science behind medication is becoming clearer

What are the benefits of painkillers? The science behind medication is becoming clearer ...

Life is more dangerous when you have the ability to feel pain. Pain tells us to use a hammer less often, wait for the soup to cool, or put on gloves in a snowball fight. Those with rare inherited diseases that leave them without the ability to feel pain are unable to protect themselves from environmental dangers, including broken bones, damaged skin, and ultimately a shorter life expectancy.

Pain is more than just a sensation in these situations: It is a protective call to action. However, excessive or long-term pain may be debilitating. So what can be done about modern medicine to reduce the stress of pain?

We and other researchers have tried to answer this question as a neurobiologist and an anesthesiologist who specialize in pain. Over the past several years, science's understanding of how the body senses tissue damage and perceives it as the pain has improved enormously.

Interestingly, while the brain utilizes different pain signaling pathways depending on the severity of the injury, there is also redundancy to these pathways. Even more intriguing, these neural pathways change and augment signals in the case of chronic pain and pain caused by conditions that affect the nerves themselves, even though the protective function of pain is no longer needed.

Painkillers work by tackling different parts of these pathways. Not every painkiller is appropriate for every type of pain, however. Because of the many and varied pain pathways, a perfect painkiller is elusive. But in the meantime, understanding how existing painkillers work helps medical providers and patients obtain the best outcomes.

Schmerzkillers that combat inflammation

A bruise, sprain, or broken bone caused by an injury all contribute to tissue inflammation, an immune response that can result in swelling and redness as the body attempts to heal. Specialized nerve cells in the area of the injury called nociceptors sense the body's inflammation and send pain signals to the brain.

Anti-inflammatory painkillers that are available over the counter work by decreasing inflammation in the injured area. These are particularly helpful for musculoskeletal injuries or other pain conditions caused by inflammation, such as arthritis.

Ibuprofen (Advil, Motrin), naproxen (Aleve) and aspirin do this by inhibiting an enzyme called COX, which plays a crucial role in a biochemical cascade that produces inflammatory chemicals, reducing the amount of pain signals sent to the brain. While acetaminophen (Tylenol) does not reduce inflammation as NSAIDs do, it does inhibit COX enzymes and has similar pain-reducing effects.

Other prescription anti-inflammatory painkillers include COX inhibitors, corticosteroids, and, more recently, drugs that target and activate the inflammatory chemicals themselves.

Medications that block inflammation will have side effects and potential health hazards, including irritation of the stomach lining and affecting kidney function. Over-the-counter medications are generally safe if they follow the directions on the bottle.

Corticosteroids like prednisone block the inflammatory cascade early on in the process, which is probably why they are so effective in relieving inflammation. However, long-term use of steroids can pose many health hazards that must be addressed by a physician.

Topical medications are used regularly.

Many topical medications target nociceptors, the specialized nerves that detect tissue damage. Local anesthetics, like lidocaine, prevent these nerves from sending electrical signals to the brain.

The sensory nerves that send messages to the skin's receptors are also targets for topical painkillers. Activating these proteins may induce particular sensations that can lessen the pain by decreasing the activity of the damage-sensing nerves, like the cooling sensation of menthol or the burning sensation of capsaicin.

These are excellent for pain directly affecting the skin because they work on the tiny nerves in the skin. For example, a shingles infection can cause the skin's nerves to become overactive and send persistent pain signals to the brain. Silencing those nerves with topical lidocaine or a huge dose of capsaicin can reduce these painful signals.

Medicina for nerve injury

Nerve illnesses, most commonly from arthritis or diabetes, can cause the nervous system to become overactive. Even in the absence of tissue damage, these injuries trigger the pain alarm. The best painkillers in these situations are those that dampen that alarm.

Gabapentin (Neurontin) is an antiepileptic medication that suppresses the pain-sensing system by blocking electrical signaling in the nerves. However, gabapentin can also reduce nerve activity in other parts of the nervous system, potentially causing sleepiness and confusion.

Antidepressants, such as duloxetine and nortriptyline, are thought to work by increasing certain neurotransmitters in the spinal cord and brain that are involved in regulating pain pathways, but they may also alter chemical signaling in the gastrointestinal tract, resulting in an upset stomach.

Doctors prescribe all of these medications.

Opioids are addictive.

Opioids are chemicals extracted from the poppy seed in the 1800s. Since then, the medical use of opioids has expanded to encompass many natural and synthetic derivatives of morphine with varying potency and duration. Some common examples include codeine, tramadol, oxycodone, buprenorphine, and fentanyl.

Opioids reduce pain by activating the bodys endorphin system. Endorphins are a type of opioid your body naturally produces that decreases incoming signs of injury and produces feelings of euphoria the so-called runners high. Opioids stimulate the effects of endorphins by targeting similar areas in the body.

Although opioids can reduce certain types of acute pain, such as after surgery, musculoskeletal injuries like a broken leg, or cancer pain, they are often ineffective for neuropathic illnesses and chronic pain.

Side effects and dangers include constipation and potentially fatal breathing suppression as a result of prolonged use of opioids, which may result in addiction and prolonged dependence. Because of these side effects and hazards, doctors prescribe all opioids.


Although cannabis has received a lot of attention for its potential medicinal uses, there isnt enough evidence to conclude that it can effectively treat pain. Because the use of cannabis is illegal at the federal level in the United States, high-quality clinical research funded by the federal government has failed.

Researchers do know that the body naturally produces endocannabinoids, a form of cannabis, to decrease pain perception. Cannabinoids may also reduce inflammation, but physicians do not recommend them over FDA-approved medications due to their lack of clinical evidence.

Matching pain to medication

While sounding the pain alarm is essential for survival, detonating the klaxon when it is too loud or unhelpful is sometimes necessary.

No existing medication is perfect in addressing pain. Matching specific types of pain to medications that target specific pathways can improve pain relief, but even then, medications may fail to work for individuals with the same condition. Further research that deepens the medical fields' understanding of the pain pathways and targets in the body might lead to more effective treatments and improved pain management.

Rebecca Seal, an Associate Professor of Neurobiology at the University of Pittsburgh Health Sciences, and Benedict Alter, an Assistant Professor of Anesthesiology and Perioperative Medicine at the University of Pittsburgh Health Sciences

The Conversation has licensed this version of the article under a Creative Commons license.

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