Hot water bottles are great for keeping you warm and cosy so we understand why they’re so popular. They have been used since the 1800s and have been the go-to therapy ever since! However, despite some research advocating hot water bottles, it's important to note the physiological responses that heat causes in the body. After all, it's no hidden secret that period pain was traditionally glossed over as part of other 'women problems,' not taken seriously, and certainly under researched.
In fact, the different hormone profiles that bathe female cells underpin the entire gender gap in medical research. Female cells react differently to even the most basic stimuli - and using heat for period pain is no exception!
How does heat therapy affect period pain?
Thermotherapy or heat therapy uses heat to target muscular inflammation and pain. You can also use cold temperatures to treat inflammation. Heat pads, hot water bottles and hot moist cloths are the most common ways of applying heat to inflammation.
Heat therapy is said to work because of its analgesic properties or its ability to bring blood to the area which can penetrate deep into the muscular tissue. However, heat therapy is also said to work because it is comforting on a psychological level. According to Lorimer Moseley “to reduce pain, we need to reduce credible evidence of danger & increase credible evidence of safety” and applying heat makes us feel safe. Why? Because the cold kills!
Despite this, there is little evidence to show that it helps alleviate pain at certain trigger points (small patches of acutely sensitive soft tissue) in the body and there is less evidence to show that it works for period pain. One study has claimed that heat can work for period pain however the researchers failed to differentiate if their exercise programme or the psychological effect of feeling warm eased their pain. This kind of testing means that other variables influence participants’ perception of pain and we can’t be certain if the heat therapy actually helped. What we do know is there are certainly drawbacks to this kind of treatment.
What is the rebound phenomenon?
One downside to heat therapy including hot water bottles is the rebound phenomenon. This effect of heat application describes how thermotherapy applications can have the opposite effect of drawing blood to the area. Applying heat locally is said to ease inflammation by vasodilation or dilation of the blood vessels. Blood and oxygen can then easily travel to the desired area to directly tackle the pain.
The rebound phenomenon occurs after about 20-30 minutes of applying the heat. At this point, the blood vessels constrict stopping oxygen and blood from flowing to the area. This means no heat can leave the cramping area and the skin is more likely to blister. Some studies suggest only applying heat in periods of 30 minutes or less, but what about prolonged or chronic pain?
Well for period pain it may not be of any help at all. Modern science has the understanding that period pain is caused by chemicals called prostaglandins. These are released to help your body excrete your uterus lining which provokes cramps as your muscles begin to contract. However, because there is a lack of blood flow to the contracting area applying heat would encourage your muscles to contract even more according to the rebound phenomenon. Meaning hot water bottles could simply be useless with certain types of pain.
Why shouldn’t I use a hot water bottle for period pain?
It’s no lie that the area around the uterus is particularly sensitive and applying heat to this part of the body can be dangerous. Moreover, there are so many horror stories of people burning or scalding themselves using their hot water bottle.
Erythema Ab Igne is just one side effect of the continuous use of hot water bottles, often referred to as “hot water bottles scars”, however, many people also contract this condition after resting their laptop on their legs, using heat pads and other heating elements.
Erythema Ab Igne is known to cause hyperpigmentation on the skin appearing as a cloudy discolouration and although it is benign, it is usually permanent. One study of Erythema Ab Igne in patients who had chronic pancreatitis found that they not only had permanent skin damage but also part of the pancreas had begun to calcify. Another study found that Erythema Ab Igne occurred in patients who regularly used heat pads in order to manage their pain. In their study, nearly all of their participants were female and of varying ages.
Another reason why you shouldn’t use your hot water bottle for your period pain is the fascia. The fascia is a connective tissue which holds your muscles in place and also helps your skin repair itself. And guess what is covered in fascial tissue? The lower back and abdomen where most women experience period pain.
The fascia is an incredibly important part of the body as it can withstand 141kg of pressure per cm² making it in an incredibly strong and durable tissue. After using a hot water bottle the fascia becomes softer and then when it cools down, it hardens. This means you have to use more heat next time to help relieve your cramps. This is particularly crucial for women who have endometriosis and other chronic pain conditions who frequently use heat for pain management.
What happens if you use a hot water bottle for period pain?
Scars and burns are other reasons why we recommend not to use heat so close to your vulva. Hot water bottles are known to cause severe damage after they burst, as the boiling hot water inside scalds the skin, resulting in frequent hospitalisations.
Although you might be using your heat pad or hot water bottle for period pain, patients with diabetes have been recommended to use them to help increase blood circulation. In one study, research looked at two separate cases of diabetes patients burning themselves in a span of three days: both suffered horrific injuries as well as infections and permanent damage to their body. This can only prove how devastating it would be to suffer these type of burns in the perineal area of the body.
What about yoni steaming?
One phenomenon that is a little more frightening involving women using heat for their vulvas is vagina steaming. If you haven’t heard of it already, yoni steaming or vagina steaming has been around for some time and those who sell this kind of steam treatment often promote their detoxifying and cleansing abilities.
They even claim it can help with period pain. However, modern medicine describes the vagina as ‘self-cleaning’ because it has the ability to literally clean itself rendering vaginal steaming pretty useless. One thing is for certain though is that they can be pretty dangerous.
Is vagina steaming safe?
One case study in Canada found that a woman had severely burnt herself after using vagina steaming to help her manage her painful prolapsed vagina. Although it’s been plastered as a glamorous treatment to have done, medical experts have said there is no evidence to support its healing properties.
Dr Vanessa Mackay, a consultant and spokeswoman for the Royal College of Obstetricians and Gynaecologists explained to the BBC that “Steaming the vagina could affect this healthy balance of bacteria and pH levels and cause irritation, infection (such as bacterial vaginosis or thrush) and inflammation. It could also burn the delicate skin around the vagina (the vulva)." Therefore using heat around your vagina is not only useless it is also incredibly dangerous.
Can I use heat for my chronic pain?
As we touched on earlier, many women use heat therapy for endometriosis and other conditions such as PCOS, adenomyosis and various other women’s health conditions. Many endometriosis experts believe that continual use of a hot water bottle may even worsen symptoms. If we go back to the impact of heat on the fascial tissue and the psychological impacts of heat therapy, it implies using heat for pain can actually be ‘addictive’.
Why shouldn't I use my hot water bottle for period pain?
We understand that endometriosis flare-ups are caused by muscular contractions as the body tries to excrete the endometrium. When heat is applied to the affected area, the fascia begins to loosen, as previously mentioned and then as it cools it hardens. According to one study, this can lead to worse endometriosis pain because it reduces the flexibility of the fascia and forms a rigid layer of tissue. It goes on to say that because heat is psychologically comforting it can create a ‘vicious cycle’ in using heat for pain. Because heat hardens the fascia, you then need higher temperatures to help the fascia and surrounding muscles relax which then hardens the fascia even more. Alongside the relaxing element of heat and the rebound phenomenon which proves heat treatment to be ineffective, it just goes to show that hot water bottles really aren’t that useful for women who have chronic pain.
What are the risks of using heat therapy?
There are many risks associated with using hot water bottles and heat of any kind for pain relief. Scars, burns as well as permanent muscular damage only scratch the surface of the harm that heat therapy does to women who suffer from severe period pain. Not only is it an impractical, and often ineffective form of treatment, but it can even worsen symptoms that women already find debilitating.
We should be able to use products without the fear of hurting ourselves, particularly during menstrual cycles. We believe more natural, kinder alternatives are out there and we want to be here to help support those women on their pain relief journey.