The redness of the skin is due to an increase in blood supply to the capillaries. When a layer of skin is shed, the new skin surface sometimes looks almost like normal skin, but unfortunately will return to the previous shade of red within a few hours. However, the real problem is not the redness itself but that the skin is dry and has lost the ability to sweat properly; the result is a dysfunction of the body’s normal temperature control and of its natural electrolyte balance.
Temperature dysregulation is a very serious problem, resulting in heat loss, water loss and possible hypothermia. The normal mechanism to regulate the body’s heat and water through sweating no longer seems to function, instead the skin transpires, which is a physical process like the evaporation of water from wet clothes and not under direct control.
You may sometimes feel that the erythematous part of the skin is getting hot. The heat sensors in the skin send a message to the brain which sends a signal to the heart to increase the flow of blood. This is the normal reaction to cool down the body. Unfortunately, your body is not really overheating, your temperature sensors are sending the wrong information. The natural response is, again, to keep pumping more blood to cool down the body. This can lead to a serious positive feedback loop in which your heart rate and blood pressure may rise to dangerous levels. Cardiac failure is a real possibility here. The good news is that the body has other temperature sensors, such as in the normal skin you still have as well as other locations. Eventually the brain reconciles the conflicting information by siding with the body’s core temperature readings. Your heart rate will start to drop and this episode of homeostatic dysfunction will be over.
There are a few things you can do to minimize these attacks. Firstly, if you are in the middle of doing something, stop it! Find a temperate environment, lie down, relax and breathe slowly and deeply like in meditation and help the heart slow down. Slow breathing also conflicts with the idea that your body is doing some form of exercise and should, therefore, be breathing more quickly; this also helps the brain discount the false temperature signals it is receiving.
If you are in a hot environment, head for an air-conditioned room; if you are in a cold place then go to somewhere warmer. Both temperature extremes are to be avoided if at all possible. If you were not doing anything physically taxing then just relax and breathe slowly till your heart slows down too. It is also worth having a thermometer close to hand. You can quickly verify that your hot flush was a dysfunction by measuring your core temperature. You should find that your core temperature is normal. However, if it is high then you should investigate whether you are suffering from a secondary infection and the start of a fever. As an aside, it is worth measuring your temperature on a daily basis as you may find that your ‘normal’ temperature is marginally higher than it used to be. This is yet another minor symptom and worth knowing what is your new baseline.
The final point to be made here is that the larger the area of red skin the greater the level of dysregulation. People who have not yet been diagnosed with erythroderma are most probably totally unaware of these problems. It is easy to walk around for days with a torso covered in erythroderma because the initial symptoms seem so mild. If you have a red rash that is expanding, go see a dermatologist as soon as possible. It may not be erythroderma, but it’s also not likely to disappear on its own.