Medication for the treatment of chronic back pain

Together with over 40 international experts, the World Health Organization (WHO) has developed comprehensive medical guidelines for the treatment of back pain that doesn't have a clear specific cause. For this purpose, the WHO evaluated and summarized studies on treatment with medications.

The researchers recommend two medicinal products for the treatment of chronic back pain:

• Patches or creams containing cayenne pepper (capsaicin) to improve blood flow
• Inflammation-reducing painkillers like ibuprofen

They tend to discourage the use of other products because there is no evidence that they work or because the risk of side effects is too high.

The medications and products that are not recommended include:

• Acetaminophen (also called paracetamol – probably hardly helps with back pain)
• Opioids (can become dependent on them, a lot of side effects)
• Antidepressants (limited effectiveness, a lot of side effects)
• Epilepsy medication (probably doesn't help, a lot of side effects)
• Muscle relaxants (can sometimes become dependent on them, a lot of side effects)
• Cannabis products (not clear how well they work)
• Herbal remedies such as devil's claw (not clear how well they work)
• Injections in the back (not clear how well they work)

The WHO recommendations are largely in line with the recommendations of other national and international professional associations.

Patches or creams containing cayenne pepper (also known as Capsicum frutescens or capsaicin) are a low-risk treatment option for back pain. They are applied or stuck onto the affected area. The capsaicin widens the blood vessels in the skin and improves blood flow. This makes the skin feel warm.

Studies have shown that creams and patches containing capsaicin can help. The researchers recorded how many people's pain was reduced by at least half. That was the case in

• 25% of people who were given a placebo treatment (a cream or patch without an active ingredient), and
• 46% of people who used a cream or patch containing capsaicin.

Products with capsaicin in them can irritate the skin and cause a burning feeling, stinging or blisters, for example. They should only be used on healthy areas of skin. It is important to wash your hands after applying the product so that the capsaicin doesn't get onto sensitive parts of the body.

When using capsaicin in this way, only a small amount enters the body and it is broken down after a few hours. Because of this, no serious side effects are to be expected. It can sometimes make your blood pressure increase briefly.

If back pain is treated with painkillers, non-steroidal anti-inflammatory drugs (NSAIDS) such as diclofenac, ibuprofen and naproxen are mainly used. They are taken as tablets, and lower doses are available without a prescription. Research has shown that these painkillers can relieve the pain somewhat. The most common side effects are gastrointestinal (stomach and bowel) problems such as nausea, belly ache or heartburn. These occur in about 5 out of 100 people who take the medication for a short time.

NSAID tablets can also lead to stomach ulcers and bleeding in the stomach. They slightly increase the risk of developing certain heart problems, too. This is particularly true for diclofenac. The risk of complications is bigger if you take the tablets for a long time or at higher doses. But it also depends on your general health. People who have (had) health problems like bleeding in the stomach, heart disease or kidney failure should talk to their doctor before taking NSAIDs.

NSAIDs are sometimes injected into a muscle. But these injections shouldn't be used because they can cause serious complications such as abscesses or nerve damage and aren't any better than tablets.

The painkiller acetaminophen (paracetamol) is another medication that is sometimes used to treat back pain. But a large, reliable study found that it was no more effective than a placebo (fake medication). For this reason, acetaminophen is no longer recommended for back pain nowadays.

Too high doses of acetaminophen can also damage the liver and cause liver failure. You should not take it if you have liver or kidney problems.

Low back pain is sometimes treated with prescription painkillers known as opioids. The best-known opioid is morphine. Other opioids include buprenorphine, codeine, hydromorphone, oxycodone, tapentadol, tilidine and tramadol. Opioids vary in strength. Morphine, for example, is a very strong opioid, while tramadol is a weaker one. Opioids are usually taken as tablets, but they are also available in the form of patches – for example, with the active ingredient fentanyl.

Opioids are very good at relieving many types of acute pain (for example, in cancer or the temporary treatment of pain after major surgery). But they're less effective for chronic pain. Research has found the following:

• Opioids can relieve chronic back pain in about 15% of those affected.
• On average, the pain only decreases by around 10%.
• Opioids do not relieve pain any better than anti-inflammatory painkillers such as ibuprofen do.

Some people become physically dependent on opioids, so these medications should only be used with great caution when treating chronic pain. In a study where people with back pain took oxycodone for 6 weeks, 10% developed symptoms of dependence that were still there after one year.

Opioids can also have side effects such as constipation, nausea and vomiting, itching, dizziness and drowsiness. If the dose is too high, they can affect your breathing and even lead to respiratory arrest (a life-threatening condition where the person stops breathing). So it is very important to follow the doctor's instructions and not to increase the dose without talking to the doctor first. This is also true for patches containing opioids (such as fentanyl patches). Like tablets, they release the medication into the bloodstream so they can have serious side effects too. If you stop using opioids suddenly, you may have withdrawal symptoms like tremors, goosebumps, sleep problems and muscle pain.

Opioids should generally not be used to treat chronic pain. They are an option if other treatments haven't helped enough or if inflammation-reducing painkillers like ibuprofen (NSAIDs) can't be used. Then they should generally be used for only a few weeks at the most – ideally as part of a multimodal treatment program where you're weaned off the medication, too.

Antidepressants are prescription-only drugs used to treat depression. Some of these medications have also been approved for the treatment of chronic pain. Most antidepressants haven't been proven to help in chronic back pain. The drug duloxetine can slightly relieve the pain.

Antidepressants have a number of side effects, including loss of appetite, nausea, a dry mouth and feeling dizzy or light-headed (low blood pressure). They can reduce sexual desire too.

Sometimes epilepsy medications such as gabapentin and pregabalin are considered for the treatment of back pain. They affect certain neurotransmitters in the brain. It is hoped that they can relieve pain that has a nerve-related cause in particular. But there is a lack of good research on whether they can actually help in the treatment of back pain. Research has found that epilepsy medications aren't clearly better than a fake medication (placebo) – not even in people whose pain comes from the sciatic nerve.

These medications can have a lot of side effects, including dizziness, exhaustion, memory and concentration problems, a dry mouth and poor balance. In rare cases, they can lead to serious side effects such as breathing problems. They also affect your ability to drive and you might become dependent on them.

Muscle relaxants are thought to relieve pain by reducing tension in the muscles. They are usually prescription-only sedatives that influence the central nervous system.

There is a lack of good research on the effects of muscle relaxants in the treatment of back pain. The research so far has led to contradictory results.

Muscle relaxants can have side effects like tiredness or drowsiness. This can affect your ability to drive, and also increase the risk of falls in older people. Taking these medications can be a problem for people who operate machinery, too. What's more, some people become dependent on muscle relaxants known as benzodiazepines.

There has been no research on the effectiveness of medical cannabis products for back pain specifically. In research on other kinds of chronic pain, cannabis products only relieved the pain a little, or not at all.

Possible side effects include temporary problems with thinking or memory, dizziness, trouble concentrating, nausea and vomiting.

There is no scientific proof that back pain is relieved by herbal products containing extracts of devil's claw, willow bark, arnica, ginger, lilies or combinations of different plants. The research so far hasn't been reliable enough to reach clear conclusions.

If other treatments for low back pain do not help, a local anesthetic is sometimes injected into the muscles or fascia.

Previous research on these injections for non-specific back pain have found that they only have a very small effect – and that this small effect only lasts a few weeks. Although side effects are rare, the injections can lead to complications such as bacterial infections. These complications may take a long time to treat.

Because it's not clear how effective the injections are and because of the possible risks, this treatment is not a good idea for people with non-specific low back pain.

In Germany, metamizole ("Novalgin") is sometimes used to treat pain. Metamizole is a fever-reducing and muscle-relaxing painkiller that is similar to the NSAIDs. There is no research on the effectiveness of metamizole in the treatment of low back pain. Medical associations consider it to be an alternative to opioids for severe low back pain. Metamizole is prescription-only in Germany.

The use of metamizole is the subject of debate because it can lead to a rare but serious side effect known as agranulocytosis. This side effect causes a big drop in the number of certain white blood cells in the body, which can be life-threatening. Possible signs of agranulocytosis include fever, a sore throat and inflamed mucous membranes. According to estimates, this complication occurs in far less than 1 in 1,000 people who take metamizole.

There are two other anti-inflammatory painkillers, known as celecoxib and etoricoxib, that work in a similar way to NSAIDs. They are COX-2 inhibitors, also known as coxibs. These medications are not approved for the treatment of back pain, so they are rarely used for this purpose – for instance, if opioids are the only other option. Coxibs are only available on prescription.