Tooth sensitivity after whitening — is it normal?

Whitening gel temporarily opens the dentinal tubules — the microscopic channels that connect the outer enamel to the nerve. Cold, hot, and even air can briefly trigger the nerve, which we feel as sensitivity. It almost always resolves within 24-48 hours. If sensitivity lasts longer than 4 days or becomes sharp pain, see your dentist — it may signal an undetected crack or recession.