Blood Pressure Medications
Cimetidine
Erythromycin may increase the level of loratadine and pseudoephedrine sulfate in the blood, although studies suggest that this interaction is unlikely to cause any problems. However, you may want to consult your healthcare provider, especially if you notice any increase in
loratadine and pseudoephedrine sulfate side effects.
Digoxin
Taking loratadine and pseudoephedrine sulfate with digoxin can increase the risk of an irregular heart rhythm (arrhythmia). Check with your healthcare provider before taking these medications together. Because this interaction is due to the pseudoephedrine component of the medication, regular Claritin (which does not contain pseudoephedrine) will not cause similar problems.
Erythromycin
Taking loratadine and pseudoephedrine sulfate with erythromycin may change the way your body handles loratadine and pseudoephedrine sulfate, increasing the level of this medicine in your blood. However, this interaction seems unlikely to cause problems for most people.
Ketoconazole
Combining ketoconazole with loratadine and pseudoephedrine sulfate may increase the level of loratadine and pseudoephedrine sulfate in your blood, although studies have not shown this to be a problem for most people.