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: Treatment response was not correlated with the incidence , time - course or severity of capsaicin - induced burning .
### Output Text:
Treatment response was not correlated with the incidence , time - course or severity of <span class="chemical">capsaicin</span> - induced burning . 