How opioid painkillers work, why they are addictive and how to avoid dependency

A study has found that one in 10 people taking opioid painkillers are dependent on them, while one in eight are at risk of prescription opioid misuse. How concerned should you be?

What are the most common opioid painkillers and how do they work?

Prescription drugs containing opioids are designed to be used as short-term acute pain relief, such as after surgery, and to help patients nearing the end of their life. They include tramadol, codeine, oxycodone, morphine, methadone and fentanyl. National Institute for Health and Care Excellence guidance states they should not be used to manage long-term chronic primary pain. Opioid medicines travel through the blood and attach to opioid receptors in our brains. This blocks feelings of pain, heightens sensations of pleasure and can reduce the anxiety and stress that pain causes.

According to the NHS, side-effects of opioid painkillers include excessive sleepiness and confusion and constipation. They make breathing shallower and slower and unresponsive to increased oxygen requirements. They have negative effects on the immune system. And they also affect people’s hormones and how they work to keep the body and the mind in balance. Some people can become more sensitive to pain (hyperalgesia) as a result of taking opioid medicines.

Why are they addictive?

Dr Lars Williams, a consultant anaesthetist and pain specialist at NHS Greater Glasgow & Clyde pain service, explains in a forthcoming issue of Pain Matters magazine that we all produce our own opioids (endorphins) that work on the opioid receptors found throughout the body’s pain system. But because opioid painkillers are a lot stronger than the opioids our bodies make, the first time we take any morphine-family drug, the effect is powerful. Each subsequent time, the effect is less powerful, as the opioid receptors become less sensitive, so you need increasingly bigger doses. This leads to physical dependence causing more pain and withdrawal symptoms if doses are reduced or stopped.

What are the signs of dependency?

They will vary from patient to patient but include taking increasingly larger doses as the body finds existing dosage insufficient to manage pain, craving the next dose; withdrawal symptoms when the prescription has run out; and an inability to cut down. Withdrawal symptoms can include palpitations, panic attacks, nausea, aches, sweating and shaking.

I’ve just had surgery and been prescribed codeine. How do I avoid dependency?

Your doctor should explain how to take your medicine safely. Read the instructions on the packet and do not exceed the stated dose or the length of time you take it for. If you are still in pain, make an appointment to see your GP to discuss how to manage your symptoms.

What should you do if you think you are overly reliant on opioid prescriptions?

If you need support for any challenges with prescription drugs, talk to your GP or contact WithYou, a drug, alcohol and mental health charity. You can speak to a trained adviser without charge and confidentially via their webchat service available at wearewithyou.org.uk .