Why is it safe?
Plain sucrose and simple sugar-based candy without toxic additives are not directly toxic. Cats lack functional sweet taste receptors (TAS1R2 is a pseudogene in felines) and show little voluntary interest in sweet foods. Plain sugar causes no acute toxicity. The real risk in candy is almost always from additives: xylitol, chocolate, raisins, macadamia nuts, or artificial flavors, not the sugar itself.
Symptoms
No acute symptoms from plain sucrose. Chronic overfeeding: weight gain, dental decay, potential contribution to diabetes.
What To Do
No action needed for small accidental ingestion of plain sugar. Before concluding candy exposure is low-risk: check the full ingredient list for xylitol, chocolate, raisins, and macadamia nuts.
Notes
Never assume candy is "just sugar", most commercial candy contains multiple ingredients. Sugar-free candy substitutes sucrose with xylitol or other sugar alcohols: a fundamentally different risk profile that requires urgent evaluation. Cats with diabetes should have zero access to any sugary foods.
Sources
→ ASPCA Animal Poison Control Center — aspca.org
→ Cornell Feline Health Center — vet.cornell.edu