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: CONCLUSIONS : Bilateral abductor paralysis is a rare complication of Botox injections for ADSD , causing difficulty with breathing upon exertion .
### Output Text:
CONCLUSIONS : Bilateral abductor paralysis is a rare complication of <span class="chemical">Botox</span> injections for ADSD , causing difficulty with breathing upon exertion . 