Tachycardia is a common and sometimes overlooked adverse effect in clinical practice. Whether it is due to direct sympathetic stimulation, reflex mechanisms, or reflex compensatory mechanisms, understanding the “why” behind medication-induced tachycardia can help prevent unnecessary workups and improve patient safety. I’ll outline my top 5 medications that cause tachycardia.
Albuterol (Beta-agonists)
Albuterol is an example of a short-acting beta-2 agonist commonly used for asthma and COPD. Although it primarily targets beta-2 receptors in the lungs, it also has activity at beta-1 receptors in the heart, especially at higher doses. This can lead to increased heart rate and palpitations. Pay attention to patients whose respiratory symptoms are out of control. Patients using frequent rescue inhaler doses or high-dose nebulizer treatments are at higher risk. If tachycardia becomes problematic, ensure that we are using appropriate controller medications to reduce the frequency of beta-agonist use.
Pseudoephedrine
Pseudoephedrine is a systemic decongestant that stimulates alpha and beta adrenergic receptors. By increasing norepinephrine release and stimulating adrenergic receptors, it can raise both blood pressure and heart rate. Patients with cardiovascular disease are particularly vulnerable. Always review over-the-counter medications when evaluating unexplained tachycardia. I can’t emphasize that enough!
Levothyroxine
Levothyroxine, especially when dosed too aggressively, can cause symptoms of hyperthyroidism, including tachycardia, palpitations, and even atrial fibrillation. Monitoring TSH and adjusting doses carefully can reduce this risk. Recall that a suppressed (low) TSH is indicative of hyperthyroidism. This is an excellent nugget for board exams!
ADHD Stimulants
Stimulants such as methylphenidate and amphetamine-based products increase dopamine and norepinephrine levels in the central nervous system and are an important class of medications that cause tachycardia. The increase in norepinephrine also stimulates the cardiovascular system, leading to elevations in heart rate and blood pressure. Tachycardia is typically dose-related and may be more pronounced during initiation or dose escalation. It is important to assess baseline cardiovascular history and monitor heart rate periodically, particularly in patients with underlying heart disease or anxiety disorders.
Modafinil
Modafinil is a wakefulness-promoting agent used for narcolepsy, shift work sleep disorder, and obstructive sleep apnea–related residual sleepiness. While its exact mechanism is complex, it enhances central nervous system activity and increases catecholamine signaling. As a result, some patients may experience increases in heart rate and blood pressure. Tachycardia is generally mild but can be clinically significant in patients with underlying cardiovascular disease or when combined with other stimulatory medications.
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