Racing Heart? Why Your Thyroid Is Overactive & Medically Approved Next Steps

A racing heart can be frightening. If it feels like your pulse is pounding, fluttering, or beating too fast for no clear reason, one possible cause is hyperthyroidism.

Hyperthyroidism happens when your thyroid gland produces too much thyroid hormone. These hormones control how fast your body works — including your heart rate, metabolism, digestion, and temperature regulation. When levels are too high, everything speeds up.

If you've noticed a fast heartbeat along with other symptoms, it's important to understand what may be happening and what to do next.

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What Is Hyperthyroidism?

The thyroid is a small, butterfly-shaped gland in your neck. It produces two key hormones:

• T3 (triiodothyronine)
• T4 (thyroxine)

These hormones regulate your metabolism — essentially how your body uses energy.

In hyperthyroidism, your body makes too much T3 and T4. This overstimulates many systems, especially your heart and nervous system.

Hyperthyroidism is not rare. It affects millions of people worldwide and is more common in women, but it can affect anyone.

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Why Hyperthyroidism Causes a Racing Heart

Thyroid hormones directly affect your cardiovascular system. When levels are too high, they:

• Increase heart rate
• Strengthen heart contractions
• Increase blood flow
• Make your heart more sensitive to adrenaline

This can lead to:

• A resting heart rate above 100 beats per minute
• Palpitations (feeling your heart pound, flutter, or skip beats)
• Shortness of breath
• Chest discomfort
• Irregular heart rhythms such as atrial fibrillation

A persistently fast heart rate is not something to ignore. Over time, untreated hyperthyroidism can strain your heart and increase the risk of serious complications.

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Other Common Symptoms of Hyperthyroidism

A racing heart is often just one part of the picture. You may also notice:

• Unexplained weight loss (despite normal or increased appetite)
• Feeling hot or sweating more than usual
• Tremors (shaky hands)
• Anxiety or nervousness
• Trouble sleeping
• Frequent bowel movements
• Muscle weakness
• Thinning skin or fine hair
• Changes in menstrual cycles
• Enlarged thyroid (goiter)
• Bulging eyes (in Graves' disease)

Symptoms can develop gradually or suddenly. Some people mistake them for stress, menopause, or anxiety disorders.

If several of these symptoms sound familiar, you can use Ubie's free AI-powered Hyperthyroidism symptom checker to quickly assess your symptoms and understand whether they may be related to an overactive thyroid before scheduling a doctor's appointment.

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What Causes Hyperthyroidism?

There are several medically recognized causes of hyperthyroidism:

1. Graves' Disease (Most Common)

An autoimmune condition where your immune system stimulates the thyroid to overproduce hormones.

2. Thyroid Nodules

Lumps in the thyroid that produce excess hormone independently.

3. Thyroiditis

Inflammation of the thyroid, often temporary, sometimes after pregnancy or a viral infection.

4. Excess Iodine

Too much iodine from diet, supplements, or medications can trigger hyperthyroidism in some people.

5. Overmedication

Taking too much thyroid hormone medication for hypothyroidism.

Identifying the cause matters because treatment depends on it.

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When a Racing Heart Is an Emergency

While hyperthyroidism is treatable, certain symptoms require immediate medical care.

Seek urgent medical attention if you experience:

• Chest pain
• Severe shortness of breath
• Fainting
• Confusion
• Very high heart rate (especially above 140 bpm at rest)
• Fever with severe symptoms

In rare cases, untreated hyperthyroidism can lead to thyroid storm, a life-threatening condition requiring emergency treatment.

If your symptoms feel severe or sudden, do not wait — seek immediate care.

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How Hyperthyroidism Is Diagnosed

Diagnosis is straightforward and based on blood tests.

Your doctor will typically order:

• TSH (thyroid-stimulating hormone) – usually low in hyperthyroidism
• Free T4
• T3 levels

If hyperthyroidism is confirmed, additional tests may include:

• Thyroid antibody tests
• Thyroid ultrasound
• Radioactive iodine uptake scan

These help determine the underlying cause.

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Medically Approved Treatment Options

The good news: hyperthyroidism is treatable. Treatment depends on your age, health, cause, and severity.

1. Beta-Blockers (Symptom Control)

Often prescribed first to manage symptoms like:

• Racing heart
• Tremors
• Anxiety

These medications do not treat the underlying cause but provide fast relief.

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2. Anti-Thyroid Medications

Drugs such as methimazole reduce hormone production.

• Often first-line treatment
• May be used for months to years
• Require regular blood monitoring
• Effective for many patients

Side effects are uncommon but can include liver issues or low white blood cell counts. Your doctor will monitor you carefully.

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3. Radioactive Iodine Therapy

A widely used, effective treatment that:

• Destroys overactive thyroid cells
• Is taken orally
• Gradually reduces hormone production

This often results in hypothyroidism later, which is treated safely with thyroid hormone replacement.

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4. Surgery (Thyroidectomy)

Less common but appropriate when:

• There is a large goiter
• Suspicious nodules are present
• Medications are not tolerated
• Severe eye symptoms occur

Surgery is generally safe when performed by experienced surgeons.

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Lifestyle Considerations

While medical treatment is essential, you can support your recovery by:

• Avoiding excess iodine supplements
• Reducing caffeine (can worsen palpitations)
• Managing stress
• Getting adequate sleep
• Eating balanced meals to maintain weight

Lifestyle changes alone cannot cure hyperthyroidism, but they can reduce symptom severity.

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What Happens If Hyperthyroidism Is Not Treated?

Untreated hyperthyroidism can lead to:

• Heart rhythm disorders (like atrial fibrillation)
• Heart failure
• Bone loss (osteoporosis)
• Muscle wasting
• Fertility issues
• Thyroid storm (rare but life-threatening)

This is why persistent symptoms should never be ignored.

The goal is not to cause alarm — but to encourage timely evaluation. Most people do very well with appropriate treatment.

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When to Speak to a Doctor

You should speak to a healthcare professional if you have:

• A racing heart without clear cause
• Ongoing palpitations
• Unexplained weight loss
• Heat intolerance
• Tremors
• Anxiety with physical symptoms
• Family history of thyroid disease

Even if symptoms seem mild, testing is simple and can provide clarity.

If anything feels severe, sudden, or life-threatening — especially chest pain or fainting — seek emergency care immediately.

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Final Thoughts

A racing heart is not something to brush off, especially when paired with other symptoms. Hyperthyroidism is a common, treatable cause that speeds up your body's systems — particularly your heart.

The condition can feel overwhelming, but it is manageable with proper medical care. Early diagnosis reduces the risk of complications and helps you feel like yourself again.

If you suspect your thyroid may be overactive, check your symptoms using Ubie's free Hyperthyroidism symptom checker and then speak to a qualified healthcare professional about your results.

Your heart — and your overall health — deserve careful attention.