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Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 7 minutes read

When we experience pain, we seek any means to relieve it. That’s how we evolved and survived as animals, though cavemen didn’t have pharmacies to get medications.

So, when wandering around the pharmacy and faced with a multitude of choices, how do we know what’s going to hit the spot? And what if we’ve exhausted what the pharmacy offers and we still haven’t gotten relief, what more can your doctor offer? Let’s talk you through painkillers available to buy at the pharmacy, and the so-called ladder of pain relief, which may require your doctor to prescribe stronger medications as you climb upwards. By knowing the different classes of painkillers, you can also combine them if you need to.

It’s also good to be aware of side effects, and if these are intolerable, there may be other medications such as ones to treat nausea with opioid medications, that help you feel more comfortable. The following relates to tablets or oral medications; we discuss gels, creams, patches and other modes of pain relief in other articles.

You may also need medications to reduce risks if you’re taking medications for a long time, such as protecting against excess stomach acid caused by nonsteroidal anti-inflammatories. Let’s start with the science behind the main classes of pain relievers, or analgesics, as we call them.

The catch-all: acetaminophen

This is the first step on the pain relief ladder, and with relatively few risks or side effects if taken as instructed. It’s well-tolerated and may be sufficient for occasional mild pain that occurs for just a brief time. For a drug that’s been around for more than 100 years, it’s not well understood how acetaminophen works or in which area of the brain it works, but it likely stops chemical neurotransmitters from transmitting a pain message.

It’s most effective if taken regularly, and for a short period of time, up to a few days. It’s preferred over ibuprofen as it’s considered safer, but it offers a similar level of pain relief.

It’s less likely to help if you have longstanding or chronic pain, such as chronic back pain or arthritis. And it’s worth trying, but evidence suggests it may not help everyone, with post-operative pain or a tension-type headache, but it will help some.

You should be careful to take no more than the recommended maximum, and beware of other products that might contain acetaminophen such as cold and flu treatments, so you don’t double-dose. The liver clears it, so if you have any liver problems, you should check with a doctor first. It causes liver toxicity if taken above the recommended dose.

Rarely may people experience stomach upset, a rash or blood disorders. You don’t need a prescription for acetaminophen, it’s available to buy from any pharmacy. But you should consult your doctor if you’re taking it for more than a couple of weeks or need to turn to it very often.

Beating inflammation: NSAIDs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of medications that work on pain and reduce inflammation. Ibuprofen and naproxen are available to buy from any pharmacy, but stronger NSAIDs such as diclofenac or indomethacin require a prescription. NSAIDs are another step one medication on the ladder of pain relief. They can be taken in place of acetaminophen or you can combine the two.

NSAIDs have a similar effect on pain as acetaminophen but can be particularly effective in cases such as arthritis, where a joint is inflamed, causing much of the pain. They are also effective for an acute flare of gout, where one joint such as the toe is inflamed and can be extremely painful for a few days or weeks.

They act on prostaglandins, a hormone released in inflammation and present in high levels in period pain. NSAIDs are the class of choice to effectively combat period pain and are best if taken a couple of days before period pain is anticipated. The ones above are effective, but mefenamic acid is another NSAID that is often prescribed.

NSAIDs can cause increased acid production in the stomach, causing some discomfort, so you should always take them with food. Because of this, they carry the risk of gastrointestinal bleeding, which means those with a history of bleeding or a stomach ulcer, or the elderly, should avoid them. If taking for several weeks or more, your doctor may prescribe a proton pump inhibitor (PPI), to reduce the risk of a stomach ulcer forming.

Newer medications specifically target COX-2 receptors, which reduces the risk of gastrointestinal bleeding, but these require prescription.

NSAIDs may also trigger certain types of asthma and can exacerbate existing kidney disease, so should be avoided in these cases.

Aspirin is sometimes included in the NSAID group but has fallen out of favor as a preferred pain relief, and its anti-inflammatory actions only kick in at a higher dose. It’s still regularly used at low dose to reduce the risk of heart disease, but this is anti-platelet action rather than anti-pain or anti-inflammatory.

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Targeting severe pain: opioids

Opioids include a wide-ranging scope of pain relief, from codeine at the mildest end, to tramadol as a medium strength, and different forms of morphine at the strongest end. Side effects become more pronounced with stronger doses – commonly constipation, drowsiness and feeling dizzy, sick or slightly out of it. Certain people seem more susceptible to this “wooziness” than others.

Opioids are only available on prescription. Mild to moderate opioids are the second step on the pain ladder and strong opioids are on the third step. They can be combined with acetaminophen or an NSAID.

Strong opioids are particularly good for ischemic pain (after a heart attack), visceral pain (organ-related, after an operation), and palliative care, when a patient has pain with a terminal illness.

Opioids carry with them a burden of addiction if taken for a long period of time – the higher the dose, the stronger the dependency. They also produce tolerance, which means that quite quickly you need to take a higher dose for the same effect.

They can become drugs of abuse. The street drug heroin is a strong opioid, used for its “high” or feeling of euphoria, but carries a risk of reduced breathing rate. In an overdose a person may stop breathing and die unless they receive an emergency antidote (naloxone). We don’t understand the brain very well, but it’s a known phenomenon that when opioids are taken by people really in pain, such as those with a terminal illness, it targets the pain center of the brain, and they are less likely to suffer euphoria or mental disturbance, or dependency and tolerance. Reduced breathing rate is weighed up as a risk against the benefits of being pain-free in patients nearing the end of their life. Nausea can be a problem with opioids, but people can be given medications to avoid this side effect.

Treating nerve injury: neuropathic pain relief

Nerve pain is approached in the same stepwise way with the ladder of pain relief. If the medications discussed above are having only minimal effect, or you’re needing a long-term solution, or side effects or risks are not acceptable, your doctor may move you on to medications that specifically target nerve, or neuropathic, pain. These are only available by prescription.

Neuropathic pain is usually more complex in its nature and is often longstanding, therefore it’s more difficult to treat effectively. You should expect to be more comfortable with pain but probably not pain-free.

The oldest of these are amitriptyline and nortriptyline, which used to be commonly used in higher doses to treat depression. They can make you feel drowsy, groggy and sluggish, and for that reason many people find them intolerable.

Gabapentin is an alternative that is usually less sleep-inducing, but at higher doses may cause grogginess. Along with carbamazepine, it can treat epilepsy, but seems slightly better tolerated than amitriptyline. They seem to block a neurotransmitter that activates the pain pathway, but it’s not well understood. A newer version with less side effects is pregabalin.

They have a cumulative effect, meaning you need to take them regularly for a few days until you see results, and build up the dose gradually until effective, then continue them regularly to keep pain under control. They may be used to reduce reliance on other pain relievers, or you could turn to the other classes for so-called breakthrough pain at times.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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