Loratadine adverse effects

Fluoxetine is an inhibitor of the cytochrome P450 isoenzymes CYP3A4 (weak inhibitor) and CYP2D6 (moderate inhibitor), by which loratadine is metabolised. Fluoxetine may therefore moderately raise loratadine levels. One study suggests that high-dose loratadine does not cause adverse cardiac adverse effects. However, more recent case reports and studies have cast some doubt over the cardiac safety of loratadine (see Table 15.2 , (p.583)). 

Drowsiness and sedation are common adverse reactions seen with the use of many of the antihistamines. Some antihistamines appear to cause more drowsiness and sedation than others. These dm may also have varying degrees of anticholinergic (cholinergic blocking) effects, which may result in dryness of the mouth, nose, and throat and a thickening of bronchial secretions. Several newer preparations (eg, loratadine) cause little, if any, drowsiness and fewer anticholinergic effects than some of the other antihistamines. Hiotosensitivity may occur with the use of the antihistamines. 

In contrast to astemizole and terfenadine, loratadine is generally believed to be free of adverse cardiac effects. However, there is some evidence that it could be associated... 

There is a case of torsade de pointes possibly due to spiramycin with the sedating antihistamine mequitazine. The situation with erythromycin and loratadine is unclear as one study found that the combination caused a very slight increase in QT interval. Both azithromycin and erythromycin raise fexofenadine levels, but this had no effect on the QT interval, or on adverse events. Azelastine, cetirizine, desloratadine, and intranasal levocabastine seem to be free of clinically relevant interactions with macrolides. 

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