The most common side effects of Claritin, as stated by RxList.com, are dry mouth, headache, fatigue and sleepiness. Other adverse effects of Claritin include wheezing, malaise, abdominal pain and shortness of breath.
Serious side effects may occur with this medication. If any of the following is experienced, the patient should contact emergency medical help: hives, swelling of the tongue, lips or face, difficulty breathing, increased heart rate, seizures, jaundice or feeling faint.
Additional side effects include blurred vision, nosebleeds, diarrhea, nervousness and skin rash. While these side effects are less severe, the patient should still contact their physician should any of these side effects occur.