Why does my back get so sore when I'm sick? The connection between immunity and pain

• It’s a result of complex interactions between your immune system and your brain called the “neuroimmune synapse”.
• Read more:
  Turning down the volume of pain – how to retrain your brain when you get sensitised

Immunology basics

• Yes, it fights off infections for us – but it also makes us acutely aware of the job it is doing.
• When our body detects an infection, our immune system releases molecules including signalling proteins called cytokines.
• Classically, we think of this as a beneficial behavioural change to help us conserve energy to fight off the infection.

Invisibly small changes

• When molecular changes occur in part of the brain linked to cognition or mood, we think and feel differently.
• If these neuroimmune synapse changes happen in the sensory processing regions of the brain and spinal cord, we feel more pain.

Immune memories

• In fact, the sick feeling we sometimes get after a vaccination is the good work our immune system is doing to contribute to a protective immune memory.
• Women, who generally have a stronger immune response than men, may be more likely to experience pain symptoms.
• Their heightened immune response (while beneficial in resisting infections) also predisposes women to a higher risk of inflammatory conditions like autoimmune diseases.

When to worry and what to do

• Mild to moderate pain is a common symptom during illness and we often notice this in the lower back.
• The good news is it usually subsides as the infection clears and the sickness resolves.
• While treating the underlying infection is crucial, there are also ways to dial down sickness-induced neuroimmune pain.

All in the mind?

• But by understanding the mechanisms of back pain during illness and by using some simple strategies, there is hope to manage this pain effectively.
• Joshua W Pate is the author of the pain science children's book series titled Zoe and Zak's Pain Hacks.