In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: This phenomenon may be interpreted as a benign , short - term and self - limiting side effect which does not contraindicate the use of risperidone or interfere with treatment .
### Output Text:
This phenomenon may be interpreted as a benign , short - term and self - limiting side effect which does not contraindicate the use of <span class="chemical">risperidone</span> or interfere with treatment . 