High Resting Heart Rate: Causes and When It's a Concern

What is a normal resting heart rate for adults?

For adults, a normal resting heart rate falls between 60 and 100 beats per minute (bpm). Many clinicians consider the lower end of this range — 60 to 70 bpm — to be favorable, particularly from a long-term cardiovascular standpoint. A heart rate consistently above 90 bpm, even if it technically falls within the "normal" range, is worth discussing with a clinician if it represents a change from your baseline or comes with symptoms.

What causes a high resting heart rate?

Many common, treatable factors can elevate resting heart rate:

Dehydration. When blood volume drops due to insufficient fluid intake, the heart compensates by beating faster to maintain circulation. This is one of the most common and easily corrected causes.

Anemia. Low red blood cell levels mean less oxygen carried per heartbeat, so the heart speeds up to deliver more. Iron deficiency is the most common form of anemia 1Ref 1Leung AKC, Lam JM, Wong AHC, Hon KL, Li X (2024).Iron Deficiency Anemia: An Updated Review.Iron deficiency anemia as a common cause of compensatory tachycardia.

Hyperthyroidism. An overactive thyroid accelerates metabolism and typically raises heart rate, sometimes substantially.

Anxiety and chronic stress. The nervous system's fight-or-flight response raises heart rate. Generalized anxiety disorder is often associated with persistently elevated resting rates 2Ref 2DeGeorge KC, Grover M, Streeter GS (2022).Generalized Anxiety Disorder and Panic Disorder in Adults.Anxiety and panic disorder as causes of elevated resting heart rate.

Caffeine. Caffeine is a stimulant that raises heart rate; the effect is dose-dependent and varies between people.

Poor cardiovascular fitness. A sedentary person's heart has to work harder to pump adequate blood, resulting in a higher resting rate. Regular aerobic exercise lowers resting heart rate over time 3Ref 3Bull FC, Al-Ansari SS, Biddle S, et al. (2020).World Health Organization 2020 guidelines on physical activity and sedentary behaviour.Regular aerobic physical activity lowers resting heart rate and improves cardiovascular fitness.

Medications. Stimulants, decongestants, some thyroid medications, and others can raise heart rate.

Fever and infection. Any illness that raises body temperature typically also raises heart rate.

Atrial fibrillation or other rhythm disorders. A less common but important cause, particularly if the high rate is irregular 4Ref 4Joglar JA, Chung MK, Armbruster AL, et al. (2024).2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation.Atrial fibrillation and cardiac rhythm disorders as causes of elevated or irregular heart rate requiring evaluation and rate/rhythm management.

At what point is a high resting heart rate dangerous?

A heart rate above 100 bpm that is sustained and not explained by a temporary cause (exercise, fever, stress) warrants evaluation. The specific concern depends on both the rate and the rhythm:

• A regular rate of 100–120 bpm with an identifiable cause (anxiety, caffeine, dehydration) is usually not a cardiac emergency, but it should not be ignored indefinitely.
• A very fast rate (above 150 bpm) at rest, especially if sudden in onset, may indicate a paroxysmal tachycardia — a rapid rhythm that starts and stops abruptly and may need treatment.
• An irregular, fast heartbeat could indicate atrial fibrillation, which carries a risk of stroke if not managed appropriately 4Ref 4Joglar JA, Chung MK, Armbruster AL, et al. (2024).2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation.Atrial fibrillation and cardiac rhythm disorders as causes of elevated or irregular heart rate requiring evaluation and rate/rhythm management.

How is a high resting heart rate evaluated?

A clinician will take a history of symptoms (palpitations, chest discomfort, breathlessness, lightheadedness), review current medications and caffeine habits, and perform a physical exam. An ECG (electrocardiogram) is standard and quickly identifies the rhythm. Common blood tests include:

• Thyroid-stimulating hormone (TSH) to check for hyperthyroidism
• Complete blood count (CBC) to look for anemia 1Ref 1Leung AKC, Lam JM, Wong AHC, Hon KL, Li X (2024).Iron Deficiency Anemia: An Updated Review.Iron deficiency anemia as a common cause of compensatory tachycardia
• Metabolic panel to assess electrolytes and hydration status

If the heart rate is intermittently elevated, a Holter monitor worn for 24–48 hours can capture episodes that do not appear during a brief office ECG 4Ref 4Joglar JA, Chung MK, Armbruster AL, et al. (2024).2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation.Atrial fibrillation and cardiac rhythm disorders as causes of elevated or irregular heart rate requiring evaluation and rate/rhythm management.

What can bring a high resting heart rate down?

Treatment depends on the cause:

• Hydration. Drinking adequate water throughout the day often helps if dehydration is the driver.
• Reducing caffeine. Cutting back on coffee, energy drinks, or tea can lower heart rate noticeably for caffeine-sensitive individuals.
• Regular aerobic exercise. Exercise is one of the most effective long-term approaches to lowering resting heart rate and improving cardiovascular fitness 3Ref 3Bull FC, Al-Ansari SS, Biddle S, et al. (2020).World Health Organization 2020 guidelines on physical activity and sedentary behaviour.Regular aerobic physical activity lowers resting heart rate and improves cardiovascular fitness.
• Treating the underlying condition. Correcting anemia, managing thyroid disease, or treating anxiety can restore a normal heart rate.
• Medications. Beta-blockers and other agents can control heart rate when an underlying rhythm disorder or other medical cause is identified and treated 4Ref 4Joglar JA, Chung MK, Armbruster AL, et al. (2024).2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation.Atrial fibrillation and cardiac rhythm disorders as causes of elevated or irregular heart rate requiring evaluation and rate/rhythm management.

A Gale primary care clinician can order an ECG and basic labs, help identify the cause, and refer you to a cardiologist if a rhythm disorder is suspected.