There are very few people living with chronic pain who gleefully swallow a handful of pills and skip happily off for the day feeling chipper and bright as a button. For the most part, people living with chronic pain don’t seem to enjoy the need to take medications – I’ve heard some say they’re worried about “not being able to tell whether I’m doing damage” when they can’t feel their pain, others say they don’t think medications are very helpful, while still others complain about rattling when they walk. But by far the biggest complaint is the medications for chronic pain have unpleasant side effects – side effects so bad that for some people, it’s just not worth taking the pills at all.
Surprisingly, although there are many studies looking at the side effects of medications, and why they occur, the effect of side effects on doing everyday activities has seldom been examined. Thankfully a group of researchers from Harvard and Johns Hopkins have taken on this task, and we now have some information about just how much side effects can get in the way of life.
What side effects do people experience?
Nausea, dizziness, headaches, constipation, weakness, cognitive fogginess, excessive sleepiness, skin itchiness and rashes, muscle twitching – you get the drift!
Why do they happen?
Many medications for pain, and particularly medications for chronic pain, exert their influence on the central nervous system – where the receptors for neurochemicals important in modulating our experience of pain are found. It would be fabulous if there were some separate receptors that only dealt with “unhelpful” pain that could be targeted, but because pain is an adaptive response designed to protect us – and because in evolutionary terms experiencing pain is crucial to our survival and has been present from early on in our evolutionary development – receptors targeted by many pain medications are found throughout the body. And particularly in the brain – hence the fogginess, sleepiness, and headaches.
What does this mean?
When prescribing medications for chronic pain, clinicians and their patients ultimately go through a process of empirical study. What this means is that because we don’t know which type of medication is most likely to help an individual, each one needs to be tried out. And the trial and error process involves establishing the balance between helpful effects – yes, pain reduction, perhaps some help with sleep – and unhelpful effects – those side effects. The process of deciding which particular combination of medications to take is absolutely personal – only the person with pain can possibly determine whether they find the balance of helpful vs unhelpful effects tolerable.
What about this study?
In this study, Martel, Finan, Dolman and colleagues (2015) sampled a group of 111 people living with chronic musculoskeletal pain. The participants were asked to report once a month, for six months, on their medication use, side effects, and pain and activity levels. Interestingly, the group selected had to have been prescribed opioids because the larger study of which this one was a small part, was designed to establish ways to improve adherence to medication taking. In addition, this group of people were considered to be at risk of prescription opioid misuse based on an assessment for this problem, but those with a current or past substance abuse problem within the past 12 months. What this means is that while the study has some interesting findings, they will not be representative of all people living with chronic pain, and results need to be interpreted in this light.
OK, OK, I’ll get on with it!
There were no differences between men and women in terms of pain intensity, mood or pain-related activity interference but women were more likely to describe side effects due to medication. Reports of side effects were no different between those taking opioid medications as well as other pain medications such as antidepressants, anticonvulsants or NSAIDs.
Now for some expected findings: people reporting greater pain-related interference were less likely to be employed, while changes in pain intensity were related to pain-related interference, and similarly, changes in mood were also associated with greater pain related interference.
After some statistical magic (multilevel modeling is horrendously complex!), these researchers examined the unique contribution of medication side effects on pain-related activity interference. What they found was that side effects contributed a unique amount to interference even after controlling for gender, pain intensity and negative mood, and even taking into account individual differences between people.
Now this is important. Medications are prescribed for pain for two reasons: to reduce pain (obviously) and it’s assumed that because pain is then lower, pain-related interference will also be lower. In other words, people will feel less pain and do more things they want to do. What this study suggests is that the burden of side effects from medications can actually ADD to the burden of disability experienced by people living with pain. Now, one way to deal with this is to reduce the number of medications a person takes. That would take care of the side effect burden – but it would also increase the pain. Both distress and disability may then increase. An alternative is to treat the side effects with something else – a bit like taking something to stop constipation when being prescribed opioids. But that in itself can create problems – because, as many people I’ve talked to mention, they really don’t want to rattle like a pill bottle from all the medications they have to swallow.
I think there are two more alternatives. One is to look at the timing of medication taking. I’ve seen many people prescribed gabapentin three times a day – but gabapentin is sedating, and people complain of the effects on driving and on concentrating at work. An alternative, and one that I’ve seen carried out very successfully for years at Burwood Pain Management Centre in Christchurch, NZ, is prescribing the same dose of gabapentin, but taking it once a day at night. A good night’s sleep is had, and the hangover effect during the day is minimised. But this requires a change in how the doctor prescribes – and some confidence to fiddle about with the timing of the dose. It also suggests that the person living with pain, his or her doctor and probably the pharmacist need to work together to develop a plan that maximises the effectiveness of medication administration.
The second is to look at reducing reliance on medication as the primary form of coping strategy for chronic pain. This solution is a vexed one. Many people living with chronic pain are afraid to reduce their use of medication. Many doctors are unaware of alternative ways of coping even though it’s evident that as many as three people in four will not obtain any benefit from medication. Worse still, many communities have few treatment providers available to help people develop nonpharmacological ways of living well with pain. I think that’s a tragedy and I think it’s time that changed.
Martel MO, Finan PH, Dolman AJ, Subramanian S, Edwards RR, Wasan AD, & Jamison RN (2015). Self-reports of medication side effects and pain-related activity interference in patients with chronic pain: a longitudinal cohort study. Pain, 156 (6), 1092-100 PMID: 25782367