Yes. The main reason is that the stress response releases a bunch of hormones, specifically cortisol and adrenaline, which cause the fight-or-flight response. A side effect of this is that the body turns off (or at least, slows down) a lot of the functions it uses to take care of itself such as the immune system and digestive system. When this happens constantly over a long period, it can absolutely cause problems because your body is constantly trying to prepare to run away from some predator instead of taking care of itself.

It goes both ways.

So the best advice probably is to stay as healthy as possible while also being able to do the things that you enjoy.

Stress causes the body to release high levels of cortisol, which can have various harmful effects throughout the body if at high levels persistently. For example, I have Central Serous Retinopathy due to high cortisol, and have been advised by my Ophthalmologist to reduce my level of stress.

Yes.

Well, there are direct effects and knock-on effects.

If you are having stress but none of the mentioned symptoms, you probably aren't having stress. Or at least not the unhealthy chronic variant.

Being stressed in healthy doses every once in a while is not bad for your health. Chronic stress is unhealthy. And that then will result in symptoms. If it doesn't, we aren't (by definition) talking about unhealthy chronic stress.

Stress itself harms your health.

It’s almost a willing choice on the part of your body. In a million little ways your body can choose to operate in “two” different modes:

(“two” actually means a multidimensional spectrum, a huge vector of floating point values)

Your body’s got High-Alert mode, which involves being ready to fight, ready to hide and strategize, but which causes more breakdown of tissues and organizational systems …

Or it can operate in Low-Alert mode which is less ready to fight, less safe in a dangerous environment, but also causes less degradation of the systems.

Ship at full battle ready — every engine turned on and hot, every sailor at his station, versus a ship at normal daily duty: some systems turned off and being repaired, some sailors snoozing in their bunks, eating.

High Alert mode is stress, basically. Or technically it’s the response to more stressors. You go into High Alert mode and you drain resources faster.

If you want to spend some time, read up on polyvagal theory.

It explains for a part how stress can cause a lot of unhealthy side effects.

stress is literally standing right behind you with a knife and fork

I have heard it simplified as "what goes in, must come out". If you are experiencing high stress without processing the stress, it will create problems for you physically. However if you are able to integrate stressful experiences mentally/emotionally, you wouldn't experience adverse effects. So it's really a matter of whether you hold onto stress or not. That said, I think anybody who is able to manage stress effectively and with a great deal of understanding is also going to be actively working to minimize their exposure to stress to what they know they can reasonably handle. There are other factors as well, such as the quality of your diet, the type of community surrounding you, etc. The Myth of Normal by Gabor Maté addresses a lot of this type of thing for anybody curious about how things are linked. Also some good videos on YT if you don't want to read the whole book haha.

Stress, especially chronic stress, can raise cortisol levels which can result in an inflammatory response which can present as things like joint pain. I also believe there is some sort of emotional connection from cortisol and/or stress that results in poor food or health choices. I think I read somewhere that in the presence of cortisol, your body will convert more energy to fat and something else having to do with an elevated blood sugar, bit I can't remember.

Exercise can lower cortisol levels even if stress is still present.

I'm not a doctor, herbalist or anybody in any sort of medical field. I just read a lot of books and ask a lot of questions. I could be totally wrong.

The short answer is yes. I've lived under considerable stress for the better part of two decades. I don't know the entire effect, but it has given me slightly higher blood pressure, and my mind is deteriorating.

My entire body hurts all the time in the joints and muscles, and I get regular tension headaches. My heart flutters, and I get dizzy spells. I also have stress-induced asthma.. I hope it means my life is shortened, and not that I simply have to live with lower quality of life.