From the Guidelines
Loratadine is unlikely to cause a slow heart rate, as it is a second-generation antihistamine with minimal anticholinergic effects. According to the expert consensus guidelines on intravenous iron uses, formulations, administration, and management of reactions 1, second-generation antihistamines like loratadine can lead to flushing, palpitations, and dizziness, but there is no mention of causing a slow heart rate. The guidelines do recommend avoiding first-generation antihistamines, such as diphenhydramine, as they can exacerbate hypotension, tachycardia, and other serious adverse events.
Some key points to consider when taking loratadine include:
- The standard adult dose is 10 mg once daily, which is generally considered safe for most people with heart conditions
- Loratadine does not readily cross the blood-brain barrier, which reduces its potential to affect heart rate
- If you're experiencing a slow heart rate while taking loratadine, you should consult your healthcare provider to rule out other underlying conditions or medication interactions
- Certain heart conditions or medications that affect heart rhythm may require caution when taking loratadine, and it's best to discuss these concerns with your healthcare provider rather than stopping the medication abruptly.
From the Research
Loratadine and Heart Rate
- Loratadine is not associated with a significant change in heart rate, according to a study published in 2007 2.
- The study found no statistically significant difference in heart rates between baseline and end-point ECGs after 30 days of treatment with loratadine 10 mg once-daily.
- Another study from 1995 compared the effects of loratadine, terfenadine, and sedating antihistamines on the cardiovascular system and found that loratadine did not produce adverse cardiovascular effects, including bradycardia (slow heart rate) 3.
- A 1994 review of cardiovascular toxicity of antihistamines noted that loratadine was one of the second-generation agents that did not produce torsades de pointes, a rare but potentially lethal arrhythmia, and was considered safe in terms of cardiac effects 4.
- A 1999 review of the cardiovascular safety of second-generation antihistamines also concluded that loratadine was safe from cardiac arrhythmia via the IKr channel, with no propensity to cause ventricular tachyarrhythmias 5.
- The cardiovascular profile of loratadine was also evaluated in a 1999 study, which found that the drug had a very safe cardiovascular profile, with an extremely low reporting rate of cardiovascular adverse events 6.