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: Grade > or = 2 nonhematologic toxicity included nausea in 17 patients , emesis in 14 patients , fatigue in 9 patients , mucositis and / or stomatitis in 8 patients , constipation in 6 patients , weight loss in 5 patients , hand - foot syndrome in 2 patients , and skin reactions in 3 patients .
### Output Text:
Grade > or = 2 nonhematologic toxicity included nausea in 17 patients , emesis in 14 patients , fatigue in 9 patients , mucositis and / or stomatitis in 8 patients , constipation in 6 patients , weight loss in 5 patients , hand - foot syndrome in 2 patients , and skin reactions in 3 patients . 