Why do our bodies ache (joints, muscles, etc.) when we are sick?

Body aches can be very common. You may feel pain in your body after exercising for a particularly long amount of time or whenever it is that you are tired. Still, this pain can also be a result of underlying pathological conditions. Most of the time, these aches are not too harmful. However, it is crucial that you get to know what is causing them so you can know when or if it is necessary to consult a doctor.

The aches one feels may vary in frequency and intensity. For some, it might be a sharp and intermittent pain, and for others, it might be a dull and persistent ache. If the body aches are because of a medical condition, then you may also notice some other symptoms. Recognizing these other symptoms is one way to find the cause of the aching.

Every living organism has a defense system in its body called the immune system. In humans, it is made up of millions of micro-level biochemical structures and processes that work together to help our bodies fight an intruding pathogen. However, for the immune system to successfully fight off disease, our body has to suffer through a number of side effects. These side effects may include a sore throat, fever, headaches, and a runny nose. Alongside these effects, you may also feel your muscles getting weak or inflamed, called myositis, and your joints getting painful and sore, called myalgia. The important thing to note is that just like every other side effect, the body ache that you feel is also generally a side effect of the functioning of your immune system, rather than being directly caused by a virus or a pathogen.

One of the main reasons that our body aches when we are sick, like when suffering from a cold, is that the body’s immune system is producing plenty of antibodies. In addition to this, killing all those viruses replicating in our cells leaves the area ‘raw’ and exposed. Antibodies, also called immunoglobulins, are proteins that are produced by our bodies whenever some outside disease enters the body. Their primary purpose is to find the intruders, also called antigens, stick to them, identify them for the immune system, and then wait for the immune system to use other cells to destroy the antigens.

These antibodies also promote the release of a chemical called histamine, which typically dilates (widens) the blood vessels near the infection. This permits for more of the body’s defenses to get at the place of the infection. There are histamine receptors in blood vessels that cause them to dilate. As these chemicals are released into the bloodstream, they can end up in the muscles or other body parts. Various body systems can have receptors to histamine that can then trigger a pain reaction.

When the immune system goes on the offensive and sends white blood cells and T cells (another type of cells that fightdiseases), there are other biochemicals called cytokines that are also released. Such chemicals find and kill abnormal cells and signal the immune cells towards the endangered area. They are also known to trigger a biochemical pathway in the body that can affect pain receptors.

Both histamine and cytokines releases can, ultimately, change the perception of pain receptors in the body. Due to this, whenever we exert our muscles or joints even just a little bit, we are much more sensitive to pain than we would be otherwise.

There are other factors that come into play as well, such as biochemicals called interleukins that relate to fever conditions and temperature increases, all of which can affect pain receptors in different ways, for example, heat receptors. The overall perception of pains and aches over the whole body can vary from person to person, and there may be other combinations of psychological, physiological, or even nutritional factors that may influence this.

As it turns out, the pain you feel is just proof of how hard your body is continuously working to keep you safe. So, if you think you’ve caught a disease, such as flu, try to get as much rest as you can and take plenty of fluids. Make sure your immune cells get all the resources they need to win the biological warfare that’s raging inside of you.