Since amlodipine and felodipine are often used to treat similar conditions and are both calcium channel blockers, commonly, patients wonder about the difference between the two. Generally, they are very similar and patients may be switched from one to the other if treatment has not been effective. For patients with kidney disease, dosage adjustments will be need for felodipine but not with amlodipine. Some studies have also suggested that felodipine is less effective in similar doses and causes more side effects.