Fast Heart Rate: 9 Causes & What to Do

A fast heart rate is generally not a serious symptom. It is usually associated with mild situations, like stress, anxiety, intense physical activity and increased caffeine intake.

Also known as tachycardia, a fast heart rate can also be a sign of a cardiac problem (like arrhythmia), a thyroid problem (like hyperthyroidism), or even lung disease (like a pulmonary embolism). 

Therefore, if you frequently feel that that your heart rate is fast, if it takes a long time to slow down, or if it occurs with other symptoms like shortness of breath, dizziness, or fainting, you should see a cardiologist to evaluate the underlying cause and initiate treatment as necessary. 

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The main causes for a fast heart rate are:

1. Intense physical activity 

It is normal for the heart rate to increase during or after intense physical activity, like volleyball, basketball or soccer. The heart needs to work harder with more activity to ensure adequate amounts of blood, oxygen and nutrients are reaching the muscles and brain 

For males, heart rate can reach up to 220 minus current age, while in women, heart rate reach up to 226 minus current age. 

What to do: You should monitor your heart rate when you are exercising, either manually or with a smart watch that measures pulse. If your heart rate goes above what it should be, or if you additionally feel symptoms like weakness, dizziness, general malaise, or chest pain, you should seek medical attention immediately. It is also important to be physically assessed by a doctor before starting any new physical activity.

2. Excess stress 

An increased heart rate is also one of the main symptoms of stress. It is the body’s natural reaction to a threatening situation, along with increased respiratory rate, muscle contraction and blood pressure. 

However, if stress is chronically felt, it can impact cortisol hormone levels and lead to other symptoms like hair loss, irritation, dizziness, acne, headache, body aches or insomnia. 

What to do: It is important to identify the source of your stress, whether it is coming from work, school or a family problem. You should engage in activities that bring you pleasure, like going out with friends, exercising or spending time on a hobby, like photography or sewing. Psychological therapy can help give you self-awareness and develop emotional stability, which can help to relieve stress. 

3. Anxiety

Anxiety is a reaction that can occur as a result of day-to-day activities, like public speaking, doing an interview and writing a test. It is associated with symptoms like a fast heart rate, shortness of breath, tremors or fear. However, when anxiety is persistent or excessive, it is possible to develop generalized anxiety disorder or a panic disorder. 

Read more about what an anxiety attack is and how to identify one.

What to do: The best way to manage anxiety and to prevent a fast heart rate is to participate in psychological or psychiatric therapy. The doctor can help you identify the underlying cause of anxiety, and initiate treatment as they see fit. Relaxing activities, like meditation or exercise, and a healthy diet can help to control anxiety. Check out our list of teas for anxiety that you can take to soothe nerves and complement your medical treatment. 

4. Cardiac problems

Many cardiac problems are associated with a fast heart rate, which is why a fast heart rate may be a sign of a heart issue. 

Arrhythmias with increases pulses occur due to abnormalities in the way electricity is transmitted through the heart. These conditions can also cause symptoms like dizziness, general malaise, nausea, and fainting. Other conditions that may result in a fast heart rate include myocardial infarct, stroke, cardiac failure or myocarditis. The heart can also be affected by other system diseases, like thyroid disease, hormonal changes or infection. 

What to do: If you notice symptoms like a fast heart rate, dizziness, weakness, shortness of breath, or chest pain, you should proceed to the emergency room immediately. Cardiac problems should be monitored by a cardiologist so that the most appropriate treatment can be initiated. In some cases, it may be necessary to undergo a procedure called an ablation, which resets the overactive area of the heart that is causing an arrhythmia. 

5. Hyperthyroidism

The thyroid is a gland that is responsible for the production of thyroid hormones. When hormones are excessively produced, hyperthyroidism emerges. One of the main symptoms of hyperthyroidism is a fast heart rate, while others include increased blood pressure, nervousness, anxiety, insomnia and weight loss. 

Learn more about how to identify the symptoms of thyroid problems

What to do: If hyperthyroidism is confirmed, you should see an endocrinologist for treatment and monitoring. Treatment may involve beta-blockers (like propranol or metoprolol) and medications that can decrease thyroid hormone levels. You should also eat a balanced diet as directed by a registered dietitian, as many foods can provide nutrients that optimize thyroid function. 

6. Lung problems

Many times, the heart rate can increase when respiratory problems are occurring. This is the body’s way to compensate for a decreased oxygen - the heart will work harder to ensure adequate oxygen is reaching all tissues in the body. One lung condition that can cause a fast heart rate is a pulmonary embolism, which is when a blood clot blocks a blood vessel in the lungs. 

Other common symptoms of a pulmonary embolism are shortness of breath, coughing, chest pain, dizziness and excess sweating. Pulmonary embolisms can occur with conditions like heart disease, cancer, surgery, clotting diseases or COVID-19. 

What to do: A pulmonary embolism is life threatening, therefore you should proceed immediately to a hospital if you notice the above symptoms. 

7. Thermogenic supplements 

Thermogenic supplements are often used for weight loss or to enhance performance during exercise. They work by increasing the body’s core temperature and speeding-up metabolism. These supplements can affect the heart, and can cause a fast heart rate, anxiety, irritation or insomnia. 

What to do: You should not use thermogenic supplements without the guidance of a registered dietitian. To burn more calories and fat during exercise, you should calculate your fat-burning heart rate (which is 70-80% of your maximum heart rate). It is important to see a doctor for a physical assessment before starting any new physical activity. 

8. Medication use

Some medications to treat the cold or flu, rhinitis, allergies, bronchitis or asthma can contain substances like pseudoephedrine, oxymetazolien, penhylephrine or salbutamol. These substances can cause side effects like a hast heart rate. 

What to do: If you notice a fast heart rate following use of the above medications, you should discontinue use immediately. If you heart rate does not recover, then you should seek medical attention immediately. These medications should only be used as directed by a doctor, following a physical assessment. 

9. Pregnancy

A fast heart rate is a common finding in pregnancy. It occurs due to physiological changes within the woman’s body that promote the supplementation of oxygen and nutrients to the baby.  

What to do: Treatment is usually not necessary, however you should attend all prenatal appointments with an obstetrician to ensure that mother and baby are healthy. Other important considerations are a balanced diet, avoiding caffiene and light physical activity, like walking or water aerobics. Women with a history of heart problems should be evaluated by a cardiologist prior to becoming pregnant.