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Anxiety can be a symptom of a medical illness and may be the first symptom.

Anxiety is a relatively common side effect of many medications.

If your anxiety is new for you, seeing a physician early on is important.

Anxiety is a response to potential danger. Sometimes, we experience anxiety when there is no danger. In that case, if the anxiety causes significant distress or impairs functioning, it may be from an anxiety disorder, such as generalized anxiety disorder or panic disorder. Anxiety disorders "are the most prevalent mental disorders" (Bandelow, 2015).

Anxiety can also be a symptom of a general medical disorder or a side effect of medication. In those cases, a primary care doctor or a psychiatrist should be consulted.

Anxiety as a Symptom of a Medical Illness: A Real Case

(Details have been modified to protect the identity of the patient.)

A patient in my family medicine office came to see me for severe anxiety. She told me that it came "out of the blue" a few weeks ago. She felt like "jumping out of her skin." She had trouble sleeping, her hands were trembling, and she was sweating despite the office air conditioning. She no longer tolerated going outdoors into the heat.

She said she had no reason to be anxious. Nothing bad was happening in her life. She had great friends, enjoyed her job, and had no financial problems.

On physical exam, I noticed a fine tremor in her hands. Her knee reflexes were overactive. Her thyroid gland on the front of her neck felt enlarged, tender, and free of lumps. Her heart rate and blood pressure were both elevated.

I told her that her severe anxiety was probably due to an overactive thyroid gland called hyperthyroidism. I placed her on medication (a beta-blocker) to slow her heart rate and lower her blood pressure. I arranged for testing the next morning. Her thyroid tests indicated hyperthyroidism. Anxiety is a very common symptom. I referred her to an endocrinologist for treatment.

He diagnosed her with hyperthyroidism due to Grave's Disease, an autoimmune disorder. She was treated with radioactive iodine administered by mouth in a hospital outpatient room. I saw her after she finished her treatment. Her anxiety had completely resolved. No psychotherapy was needed.

This is a good example of anxiety due to a general medical disorder. If she had initially seen a therapist for therapy for her anxiety, a diagnosis of hyperthyroidism would probably have been delayed. It is important to identify it early because untreated hyperthyroidism can result in a thyroid storm, which is a medical emergency that can result in death.

Medical Illnesses and Medications That Can Cause Anxiety

When should you see a physician for new-onset anxiety? In 2018, the Cleveland Clinic published an article on this topic on its website (Cain, 2018). They indicated that a medical cause of anxiety should be considered if you have not experienced an anxiety disorder before you were an adult (most anxiety disorders begin during adolescence or shortly thereafter), there is no family history of an anxiety disorder, there have been no significant recent life changes, or the anxiety began at the time physical symptoms began.

During a physical exam, a physician may uncover abnormal vital signs or other physical abnormalities such as an excessive drop in blood pressure upon standing from a sitting or lying position, cool or flushed skin, or other physical changes due to problems with the autonomic nervous system (Cain, 2018).

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There are a large number of medical illnesses that can have anxiety as a symptom of the illness (not just being anxious about being ill). Here are some examples: Lyme disease (infection from a tick bite), minor head trauma, a brain tumor, vitamin B12 deficiency, Alzheimer's Disease, a chronic pain syndrome, a tumor of an adrenal gland, and many others.

Less commonly, anxiety may be the only symptom at the onset of a general medical illness. Numerous studies have shown that depression or anxiety are the most common affective prodromes of medical disorders and are "consistently reported in Cushing's syndrome (excessive cortisol production), hypothyroidism (low thyroid hormone), hyperparathyroidism (overactive parathyroid gland), pancreatic and lung cancer, myocardial infarction (heart attack), Wilson's Disease (abnormal buildup of copper in the body), and AIDS" [Writings in parentheses were added for clarification] (Cosci, 2014).

Anxiety can also result as a side effect of medication. Research has shown that anxiety and jitteriness can develop after starting an antidepressant such as an SSRI. This is more common in patients with major depressive disorder (MDD) or with a first-degree relative with MDD (Harada, 2014). This is a paradox because many antidepressants are also used to treat anxiety disorders, not just depression

Additional examples of medications that can cause anxiety as a side effect include: stimulants such as dextroamphetamine (for ADHD), high-dose or prolonged use of prednisone (e.g., cancer treatment), bronchodilators (e.g., albuterol inhaler), combination birth control pills, topiramate (anticonvulsant used for seizures and bipolar disorder), triptans (for migraines), modafinil (narcolepsy, sleep apnea), nasal decongestants (e.g., pseudoephedrine), during withdrawal from benzodiazepines (e.g., lorazepam), and many others.

The bottom line is that general medical illnesses may have anxiety as a symptom, and anxiety can be a side effect of medications. So, if you have a new onset of anxiety, it would be prudent to see a primary care doctor or a psychiatrist (they are medical doctors) to find out if there is a medical cause for the anxiety. If there is no medical cause, referral to a therapist is appropriate.

Bandelow B, Michaelis S. Epidemiology of anxiety disorders in the 21st century. Dialogues Clin Neurosci. 2015 Sep; 17(3):327-335. doi:10.31887/DCNS.2015.17.3/bbandelow

Cain R. Is a hidden medical condition causing your anxiety? Cleveland Clinic. Published Jun 22, 2018. Accessed February 13, 2026. https://health.clevelandclinic.org/is-a-hidden-medical-condition-causin…

Cosci F, Fava GA, Sonino N. Mood and anxiety disorders as early manifestations of medical illness: a systematic review. Psychother Psychosom. 2015; 84(1): 22-29. doi:10.1159/000367913

Harada T, Inada K, Yamada K, et al. A prospective naturalistic study of antidepressant-induced jitteriness/anxiety syndrome. Neuropsychiatr Dis Treat. 2014 Nov 10; 10: 2115-2121. doi:10.2147/NDT.S70637

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