Desloratadine and loratadine are both second-generation antihistamines used to treat allergic reactions. Here are the differences between them :

1.**Chemical Structure**:

   - Desloratadine is the active metabolite of loratadine. Loratadine undergoes metabolic transformation in the body to become desloratadine, which is considered to be the primary active form.

2. **Pharmacokinetics**:

   - Desloratadine has a longer half-life than loratadine, which means it stays in the body for a longer period of time. This can potentially lead to once-daily dosing compared to loratadine, which may require more frequent administration.

3. **Onset of Action**:

   - Desloratadine may have a faster onset of action compared to loratadine, providing relief from allergy symptoms more quickly.

4. **Sedative Effects**:

   - Both desloratadine and loratadine are considered non-sedating antihistamines, but loratadine may have a slightly higher potential for causing sedation in some individuals.

5. **Side Effects**:

   - The side effect profiles of both drugs are similar, but desloratadine may have a slightly better tolerance profile in some patients.

6. **Dosage**:

   - The dosage forms and strengths may vary. Desloratadine is available in tablets, oral disintegrating tablets, and syrup, while loratadine is available in tablets and syrup.

7. **Approved Uses**:

   - Both drugs are used to treat symptoms of allergic rhinitis, urticaria (hives), and other allergic conditions. However, the specific approvals may vary by country and regulatory authority.

It's important to note that while these drugs are similar, the choice between desloratadine and loratadine may depend on individual patient factors, including tolerance, dosing convenience, and specific medical history. Always consult with a healthcare professional for advice on the most appropriate medication.