The short explanation
Sudden sensitivity to cold water is usually caused by exposure of the inner layer of the tooth, called dentine, which has tiny channels leading to the nerve. This can happen when gums pull back and expose the root, when enamel wears away from hard brushing or acidic foods, or when a tooth has a crack, a new cavity, or a lost filling. Sensitivity toothpaste can help many people, but it works over time and does not fix the cause. If sensitivity is sudden, sharp, in one tooth, or lingers after the cold is gone, it is worth seeing a dentist, because it could mean decay, a crack, or a nerve problem that needs treatment.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- Hard brushing, brushing with a hard brush, grinding teeth at night, and frequent acidic foods or drinks can wear enamel.
- Gum disease and age can cause gums to recede.
- Recent dental work can cause temporary sensitivity.
- Pain that keeps you awake or throbs suggests a nerve problem.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you the cause of your sensitivity. A dentist needs to examine your teeth.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- What is causing my sensitivity?
- Is there decay or a crack?
- Would sensitivity toothpaste help me?
- Am I brushing too hard?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Get help the same day
- Get same-day dental care if you have severe throbbing pain or swelling of the face or gum.
Book an appointment soon
- See a dentist within a few days if sensitivity is sudden, in one tooth, or lasting.
Raise it at a routine appointment
- Book a routine dental check-up if sensitivity is mild.
Sources
The evidence this explanation is built on.
- Oral health World Health Organization
- Gum disease NHS
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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