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: Adverse effects included constipation , morning drowsiness , dizziness and rash , and resulted in withdrawal from the study by three men .
### Output Text:
Adverse effects included constipation , morning drowsiness , dizziness and rash , and resulted in withdrawal from the study by three men . 