What sides effects expected if I accidently took 2 Claritin a few hours apart?

You should be fine but really you are only suppose to take them one a day. Try to stick to that schedule.

Symptoms of an Overdose: Based on the cases that have been reported, the following symptoms of a Claritin overdose are possible:

Drowsiness; Rapid heart rate (tachycardia); Headaches; Feelings of a rapidly or forcefully beating heart (known as heart palpitations); Unusual body movements or muscle contractions.

Treatment for an Overdose of Claritin: The treatment for a Claritin overdose will also vary. If the overdose was recent, the doc may give certain medicines or place a tube into the stomach to "pump the stomach." However, once the drug has been absorbed into the body, there is no treatment that can remove it quickly. Therefore, in these cases, treatment typically involves supportive care, which consists of treating the symptoms that occur as a result of the overdose. For example, supportive treatment options for an overdose of Claritin may include:

Fluids through an intravenous line (IV); Medications to control a fast heart rate; Other treatments based on complications that occur.

It is strongly recommended to seek medical attention immediately, hope the above info is of help?