Hi, I'd like to help you with your question.
Yes, anxiety can cause your body to react by getting sick. It is usually because anxiety causes stress on the body and an increase in cortisol, which is secreted when you are upset or anxious.
A study done in 2008 concluded that anxiety can cause an increase in migraines, digestive illness (more acid in the stomach for example leads to stomach upset), muscle aches (from tension) etc. It can also reduce your resistance to colds and the common flu.
Anxiety, however, cannot give you diseases such as cancer or heart disease. Although it can raise your blood pressure and affect your stress level, it cannot cause a disease itself.
The good news is that treatment of anxiety can greatly reduce your chances of feeling ill. Therapy and relaxation techniques help to control the anxiety and contribute to the reduction of the effects of anxiety and stress on your body.
I hope this has helped,
If you do feel anxious and the doctor has ruled out a physical cause, then it is most likely anxiety causing your symptoms.
But if you do not feel anxious (and do not have anxiety or an anxiety diagnosis at all) then it may be something else. If your doctor has ruled out a physical cause and does not feel you have anxiety, then ask him/her if they think it could be emotional.
Also, you may want to consider an evaluation by a therapist to see if there could be another cause besides anxiety and to also rule out you having anxiety. Once a physical cause is ruled out, then it could be something related to your emotional health such as too much stress in your life.
Yes, you can still have physical symptoms. It is often the case with anxiety that you are tense physically without realizing it. Many people with anxiety do not realize how tense they really are physically, which is why relaxation is such an important part of recovery from anxiety.
So can it cause upset stomach nausea and lightheadedness?
Yes, it can. Matter or fact those are very common complaints for people with anxiety.