Yes. Hyperthyroidism can cause tachycardia, meaning the heart beats faster than usual. Extra thyroid hormone can speed up the body's processes and affect heart rhythm, causing a racing pulse or sometimes an irregular heartbeat. Other symptoms may include shaking, sweating, feeling unusually warm, or losing weight without trying. Because a fast heartbeat has many possible causes, ongoing or worrying symptoms should be checked by a healthcare professional.
How Does Hyperthyroidism Affect Heart Rate?
Hyperthyroidism occurs when the thyroid gland produces more thyroid hormone than the body needs. The thyroid is a small, butterfly-shaped gland at the front of the neck. Its hormones help regulate metabolism, body temperature, and several important functions, including the heartbeat.
When thyroid hormone levels are too high, many body processes speed up. This can cause the heart to beat faster than usual, even when a person is resting. Some people notice a rapid pulse during ordinary activities, while others experience a pounding or fluttering sensation in the chest. According to Mayo Clinic, hyperthyroidism can cause both a fast heartbeat, known as tachycardia, and an irregular heartbeat.
The degree of the heart-rate change varies. Hyperthyroidism may cause a persistently fast heartbeat, episodes of palpitations, or changes in the heart's rhythm. These effects depend on the individual's circumstances and the underlying thyroid condition.
What Does Hyperthyroidism-Related Tachycardia Feel Like?
A fast heartbeat may be noticeable, but it does not always cause obvious discomfort. Some people feel their heart racing or pounding, while others notice that their pulse seems faster than usual during rest or everyday activities.
When tachycardia occurs alongside other features of an overactive thyroid, the symptoms may include:
- A racing, pounding, fluttering, or unusually fast heartbeat.
- Shaky hands or trembling.
- Excessive sweating or feeling unusually hot.
- Unexplained weight loss, sometimes despite an increased appetite.
- Nervousness, irritability, or difficulty sleeping.
- Muscle weakness or unusual tiredness.
- More frequent bowel movements.
These symptoms can occur in different combinations. A person does not need to experience all of them, and their presence does not establish that a thyroid problem is responsible. Other medical conditions, medicines, and everyday triggers can also cause a fast heartbeat.
Can Hyperthyroidism Cause an Irregular Heartbeat?
Yes. In addition to increasing heart rate, excess thyroid hormone can be associated with abnormal heart rhythms, or arrhythmias. One important example is atrial fibrillation, a condition in which the upper chambers of the heart beat irregularly. This may produce a rapid or uneven pulse and can increase the risk of blood clots and stroke.
The National Health Service (NHS) identifies atrial fibrillation and heart failure among the possible complications of an overactive thyroid. These complications do not occur in everyone with hyperthyroidism, but they help explain why persistent tachycardia should not be ignored.
Age can also affect how thyroid problems become noticeable. Older adults may have less obvious symptoms, such as weakness, tiredness, weight loss, or an irregular heartbeat, rather than the more familiar signs of feeling hot or unusually restless. As a result, thyroid-related changes in heart rate may not always be easy to recognize.
Does a Fast Heartbeat Always Mean Hyperthyroidism?
No. Hyperthyroidism is one possible cause of tachycardia, but a fast heartbeat can occur for many other reasons. Physical exertion, fever, dehydration, emotional stress, certain medicines, and stimulants such as caffeine may contribute to a faster pulse. Heart rhythm disorders and other medical conditions can also be responsible.
Palpitations and tachycardia are related but different terms. Palpitations describe the sensation of noticing your heartbeat, such as pounding, fluttering, or racing. Tachycardia describes a faster-than-usual heart rate. Palpitations can occur without a sustained rapid heart rate, and tachycardia can sometimes occur without being felt.
According to Mayo Clinic's guidance on heart palpitations, possible causes include stress, strenuous exercise, some medicines, and thyroid hormone changes. Therefore, a fast pulse alone cannot show whether the thyroid is responsible.
How Do Doctors Check Whether Hyperthyroidism Is Causing Tachycardia?
Healthcare professionals assess the heartbeat alongside other symptoms, medical history, medicines, and examination findings. They may ask when the rapid heartbeat began, whether it occurs at rest or during activity, how long episodes last, and whether other symptoms have developed.
Depending on the findings, an evaluation may include:
- Pulse and physical examination: These help assess the heart rate, rhythm, and other physical signs that may be relevant.
- Thyroid blood tests: Tests such as thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) help assess thyroid function.
- An electrocardiogram (ECG): This records the heart's electrical activity and can help identify an abnormal rhythm.
- Heart monitoring: If symptoms come and go, a clinician may recommend monitoring to help capture episodes that are not present during an office visit.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that doctors use a medical history, physical examination, and appropriate tests to diagnose hyperthyroidism and identify its cause. Symptoms alone are not enough to confirm the condition.
How Is Tachycardia From Hyperthyroidism Treated?
Treatment focuses on the cause of the excess thyroid hormone and the effects it has on the heart. The appropriate approach depends on the underlying thyroid condition, symptoms, health history, and other individual factors.
A healthcare professional may prescribe a beta-blocker to reduce symptoms such as a rapid heartbeat, tremor, and nervousness. These medicines can help control symptoms while treatment for the thyroid problem takes effect. They do not stop the thyroid from producing excess hormone.
Depending on the cause, treatment for hyperthyroidism may involve antithyroid medicines, radioactive iodine treatment, or surgery. The choice is individualized, and not every treatment is suitable for every person. MedlinePlus, a service of the US National Library of Medicine, describes these options and explains that beta-blockers may help relieve rapid-heartbeat symptoms while other treatments take effect.
As thyroid hormone levels return toward normal, thyroid-related symptoms may improve. However, the response and timing vary. A rapid or irregular heartbeat that continues despite treatment may need further assessment to determine whether another cause or a separate heart rhythm problem is involved.
When Should You Seek Medical Help for a Fast Heartbeat?
Arrange a medical assessment if your heartbeat is repeatedly faster than usual at rest, episodes of palpitations keep returning, or a rapid pulse occurs with other possible symptoms of hyperthyroidism. It is also important to seek review if symptoms are becoming more frequent, interfering with daily activities, or developing after a change in medication.
Seek emergency medical care if a racing or pounding heartbeat occurs with chest pain or discomfort, fainting, severe shortness of breath, or severe dizziness. These symptoms can indicate a serious problem and should not be attributed to the thyroid without assessment.
A sudden rapid heartbeat accompanied by high fever, marked confusion, or severe illness also requires emergency assessment. A rare complication of uncontrolled hyperthyroidism, called thyroid storm, can be life-threatening and needs immediate medical treatment.
Recognizing the possible connection between hyperthyroidism and tachycardia can help guide the right evaluation. With appropriate testing and treatment, clinicians can address excess thyroid hormone and assess whether additional care is needed for the heart.