Heat therapy is when any sort of heat is used to help manage pain in the body on its own or in combination with analgesics.
Local heat - which is a device placed on a specific area of the body e.g. heat pack, wheat bag, hot water bottle
Systemic heat - heating the whole body e.g. hot shower, bath, sauna, jacuzzi
When to use heat?
Heat is mostly used for non-inflammatory pain. Ideal for:
muscle soreness from over exertion, delayed onset muscle soreness (DOMs)
muscle pain, spasms, cramping or stiffness
‘hurts everywhere’ sensitivity and pain from conditions like fibromyalgia
When not to use heat?
It is not recommended to use heat for an acute infection or acute inflammation e.g. arthritis or lupus acute flare in a joint, or fresh new injury like ankle ligament sprain or muscle strain. What for the inflammatory phase to pass before introducing heat.
How does heat help?
Heat is a comfort, it's soothing and this reassures the brain and thinks its safe, which acts like an analgesic reducing pain (this isn’t just a psychological affect, its about neurology!)
Heat can also affect the tissue directly and its thought cell processes are thought to speed up which can promote healing faster
Heat can help relax muscles – and reduce muscle spasm and tone by improving elasticity
It can increase blood flow to the area which is thought to help ‘flush’ out toxins – limited research on this
Risks of using heat
You can burn your skin with repeated use of heat packs in the same area, especially if you have decreased sensitivity. It is also common when using heat in the same area that you gradually feel the need to have the heat pack hotter and hotter to feel the same level of relief as your tolerance increases. This can be dangerous to your skin and lead to superficial skin burns.
EAI is a skin reaction caused by chronic exposure to infrared radiation aka heat. It creates a web type pattern that easily blanches (go white when you press it). Women are more likely to experience this than men and more common in the elderly with sensory issues, although it can be seen in other settings such as laptop burns too.
It is not fully understood what happens, but it is thought that thermal radiation exposure can damage the superficial blood vessels causing them to dilate (widen) which causes the redness. Brown dark marks are thought to be from red blood cells leak into surrounded tissues, alongside the deposition of hemosiderin (iron forming chemical). Then they think the web like/net like pattern of erythema is due to the distribution of red blood vessels in the skin layer.
If the area is only mildly affected with slight redness, the condition will resolve by itself over several months if you reduce the amount of heat applied to that area. If the condition is severe and heat is continued to be used over that area, the skin stays pigmented and it starts to thin (atrophy). At this stage it is then unlikely to resolve. It can feel itchy and very rarely sores can also develop which should be assessed by a doctor. There is a some research that shows an increase risk that squamous cell carcinomas may form. If there is a persistent sore that doesn't heal or a growing lump within the rash, a skin biopsy should be performed to rule out the possibility of skin cancer.
My favourite heat packs?
(Some of these include an Amazon Affiliate link that gives me a tiny tiny percentage but does not change the price for you but helps support my business running costs)
My Yuyu bottle - buy here Amazon or direct from YuYu This is probably featured the most in my stories as its pretty much glued to me every night. I love it as stays warm for the longest amount of time making it perfect for night time. It also is an amazing length so you can either lie it longwise across your body to hit multiple body parts or wrap it around your body so you can get 360 heating affect of your torso.
Wheat bag - buy here I love this for a quick blast of heat if I don't feel I have the energy or can't be bothered to wait to fill the kettle up and boil. It only takes 90 seconds - 2 minutes in the microwave and is great for just everyday heat. Definitely make sure you follow whatever your heat pack advises you to how long to heat it, as they can explode or burn you if overheated!
Plug in/electric heat pad - buy here This is great for sitting at my desk with as it stays hot for as long as you have it turned on. I also have it handy in bed for if it's a tough pain night, and I don't feel well enough to downstairs to re-fill my yuyu bottle. However I have been warned and heard horror stories about some of these catching fire so I always unplug in-between uses to be on the safe side and if I feel the plug part get overheated from continuous use turn it off and switch to another heat pack. I also don't find it as hot as a hot water bottle which is probably better for my skin, but not ideal for my pain.
Mini normal hot water bottle - buy here This is an essential for travelling as sometimes asking the barista in a coffee shop to fill up the super long yuyu bottle is a bit much. It's also much smaller and lighter to carry around and more easily tucked into your pants. That being said I definitely fly with my yuyu bottle and just take the judgement from the flight attendants when I ask them to fill it up for me!
Stick on heat pads - buy here As discussed above, I have zero shame for walking around in public with a hot water bottle in my pants, but sometimes this isn't appropriate or you can do without a full heat pack but still want a little heat. These are ideal for that, they don't get super hot but they are better than nothing. I don't actually like sticker them to my skin (EDS skin/mast cell problems) but I just put them down my pants as I want them over my bladder or stomach. Some come with a little belt that they sit in instead so it depends what you buy. They are also single use, sorry environment but I think if you don't use them all the time the world will forgive us.
Heating massage cushion - buy here So this is technically a massage device but it has an optional heat element too. I love this on my back, shoulders or stomach and the heat is actually a really nice element to the massage function. It gradually builds up and helps your muscles relax which then makes it extra beneficial for the muscle release too!
Heat is a great form of pain management and definitely worth having in your toolbox. Personally I use heat for shoulder, back and abdominal/bladder pain the most. EAI however is something very common with chronic conditions like chronic bladder pain, endometriosis, chronic back pain and gut disorders where heat is applied to the same area daily due to extreme pain. I think its important to be aware that the damage to the skin can cause long term damage as this was never something I was aware of until it happened to me. I try to be mindful in alternating the type/level of heat I use, and where I place it to try to limit this.