A pounding heart at 2 a.m. A stomach that turns before every meeting. Hands that shake when you are not cold. Anxiety is felt in the body as much as in the mind, and the physical side is often what sends people looking for answers.
The difficulty is that the same symptoms can come from a medical condition, a medicine or too much caffeine. This article covers what anxiety can do to the body, what else can cause the same sensations, and which symptoms need a doctor or a 911 call. For the mental and emotional side, see what anxiety feels like.
What physical symptoms can anxiety cause?
Quite a range. The Merck Manual's overview of anxiety disorders lists these physical symptoms:
- Stomach and gut: nausea, vomiting and diarrhea.
- Breathing: shortness of breath or choking.
- Heart: palpitations and an accelerated heart rate.
- Muscles and chest: muscle tension, and chest pain or tightness.
- Whole body: dizziness, faintness, sweats, and hot and cold flashes.
The American Psychiatric Association's list adds fatigue and sleep disturbances. MedlinePlus, in its article on heart palpitations, names anxiety, stress, panic attack and fear among the causes.
Several items on this list are also warning signs of a medical emergency. That is why the sections below matter more than the list.
Why does the body react this way?
Anxiety involves the body's stress response. MedlinePlus explains that when you are stressed, your body releases certain hormones, and that these can raise your blood pressure, heart rate and blood sugar. The reaction is sometimes called the "fight or flight" response.
That accounts for a faster heartbeat in general terms. The sources behind this guide do not map each symptom to a specific hormone, so this article does not either. The practical point is that these are physical events in the body.
Which medical conditions can look like anxiety?
Several. The Merck Manual states: "Anxiety can be caused by a medical disorder or the use or discontinuation (withdrawal) of a medication." Among the disorders it lists:
- Heart disorders, such as heart failure and abnormal heart rhythms (arrhythmias).
- An overactive thyroid or adrenal gland.
- Lung disorders, such as asthma, chronic obstructive pulmonary disease (COPD) and sleep apnea.
MedlinePlus likewise notes that some palpitations are due to an abnormal heart rhythm, which may be caused by heart disease or an overactive thyroid, among other things. This is why the American Psychiatric Association says, about anxiety in general: "The first step is often to see your doctor to rule out medical conditions that may cause similar symptoms."
A checkup does not mean your anxiety is being dismissed. It means anxiety is being considered properly, alongside everything else.
Can caffeine, medicines or other substances cause these symptoms?
Yes. The Merck Manual's list of substances that can cause anxiety includes caffeine, stimulants such as amphetamines, cannabis in some people, many prescription medications such as steroids, some over-the-counter medications such as antihistamines and decongestants, and some over-the-counter weight-loss products that contain guarana or caffeine. Withdrawal from alcohol or from sedatives such as benzodiazepines is on the list too.
MedlinePlus says that for most people it is not harmful to consume up to 400 mg of caffeine a day. Too much can cause restlessness and shakiness, insomnia, a fast heart rate and anxiety. It advises checking with your health care provider about whether to limit or avoid caffeine if you have anxiety. Its article on palpitations lists caffeine, nicotine, excessive alcohol and decongestant medicines such as phenylephrine or pseudoephedrine among the causes.
Do not stop or change a prescribed medicine because of this list. If you suspect a medicine is involved, ask the prescriber or a pharmacist. That decision is made with them.
When is chest pain or trouble breathing an emergency?
Treat it as one whenever it is new, severe or unexplained. None of the sources behind this guide offers a way to tell a heart attack from anxiety or panic by symptoms alone. Do not try to work it out at home. The American Heart Association says to call 911 if you have:
- Chest discomfort, most often in the center of the chest, that lasts more than a few minutes or goes away and then returns.
- Discomfort in the arms, back, neck, jaw or stomach.
- Shortness of breath, with or without chest discomfort.
- A cold sweat or nausea.
For women, the Heart Association adds a list of less typical signs that includes anxiety, nausea, vomiting and unusual tiredness. So feeling anxious does not rule a heart attack out.
The National Heart, Lung, and Blood Institute is direct: "Call 9-1-1 for emergency medical care, even if you are not sure that you're having a heart attack." MedlinePlus gives the same instruction for palpitations that come with chest pain, shortness of breath, unusual sweating, dizziness or loss of alertness.
Panic or anxiety is a conclusion a clinician reaches after a medical evaluation. A past diagnosis of panic does not rule out a heart problem later, so new or different symptoms need to be checked each time.
When should you make a regular appointment?
The sources name a few clear cases. MedlinePlus is specific about palpitations: "If you have never had heart palpitations before, see your provider." It also says to contact your provider right away if you have new or different palpitations. For anxiety itself, MedlinePlus says to contact your provider if you frequently worry or feel anxious, especially if it interferes with your daily activities.
Expect questions. The Merck Manual says doctors ask about drug and medication use as a possible cause of anxiety, do a physical examination, and may order blood and other tests to check for medical disorders that can cause anxiety. MedlinePlus says that for palpitations you may be asked when they occur, whether you have other symptoms, and whether you consume caffeine, stimulant drugs or excessive alcohol. As a general suggestion, it can help to think about those answers beforehand and to bring a list of everything you take.
Where does therapy fit once a doctor has checked?
Physical symptoms on their own are a question for a physician. Therapy becomes an option when medical causes have been looked for and anxiety is part of the picture, or when fear of the sensations has become a problem of its own. If worry about what a symptom means is taking over, see health anxiety. If the symptoms come in sudden surges, see panic attacks.
Dr. Rabin is a licensed clinical psychologist who offers anxiety therapy in Brookline and by telehealth across Massachusetts. Her approach looks at what drives the anxiety as well as how to respond to anxious thoughts and physical sensations in the moment. The practice also has a guide to mindfulness practices for anxiety. You can request a free consultation of about 15 minutes through the contact page.
Keep reading
Sources
- Merck Manual Consumer Version (Barnhill JW), Overview of Anxiety Disorders (full review April 2026)
- American Psychiatric Association, What are Anxiety Disorders? (physician review May 2026)
- MedlinePlus, Stress (last updated October 20, 2023)
- MedlinePlus Medical Encyclopedia, Heart palpitations (reviewed June 4, 2026)
- MedlinePlus, Caffeine (last updated September 8, 2021)
- American Heart Association, Warning Signs of a Heart Attack (last reviewed December 12, 2024)
- National Heart, Lung, and Blood Institute, Heart Attack: Symptoms (last updated March 24, 2022)
- MedlinePlus Medical Encyclopedia, Generalized anxiety disorder (reviewed April 19, 2025)
Last reviewed October 2026. This guide is general information, not medical advice or a diagnosis. If you are in crisis, call or text 988, or call 911 in an emergency.
