Why Does My Tooth Hurt When I Drink Cold Water?

How long the pain lasts after the cold hits matters more than how sharp it feels.

Quick Answer

A sharp zing that disappears within a few seconds of cold usually means exposed dentin from worn enamel, receding gums, or a small cavity. Pain that lingers longer than 30 seconds, or throbs afterward, suggests the nerve inside the tooth is inflamed or dying and often needs a root canal. The duration is the clue.

The five-second rule

Time it. If the discomfort vanishes almost as soon as you swallow, the nerve is healthy and just poorly insulated. That is classic sensitivity, and it is manageable.

If the ache hangs on for half a minute or builds into a throb, the nerve itself is inflamed. That does not settle on its own, and it is the difference between a sensitivity toothpaste and a root canal.

What exposes the nerve

Under your enamel sits dentin, threaded with microscopic tubes that run to the nerve. Anything that thins enamel or uncovers the root lets cold travel down those tubes. Hard brushing, acidic drinks, grinding, and receding gums are the usual culprits.

A cracked tooth or a failing old filling does the same thing in one spot. If only one tooth reacts, suspect a crack or decay rather than general sensitivity.

What you can do at home

Switch to a soft-bristled brush and stop scrubbing. Use a toothpaste made for sensitivity, which plugs those tubes over a couple of weeks of consistent use. Cut back on soda, citrus, and wine, and rinse with water after.

If you grind at night, a nightguard protects what enamel is left. See how to stop grinding your teeth.

When to call a dentist

Book a visit if the pain lingers, wakes you at night, focuses on one tooth, or comes with swelling. Those point to decay, a crack, or nerve damage, and each gets worse and more expensive with time.

Our guides on sensitive teeth causes and gum recession go deeper on the fixes.

Frequently Asked Questions

Is cold sensitivity in one tooth serious?

It can be. Sensitivity in a single tooth more often points to a cavity, crack, or failing filling than to general enamel wear, so it is worth having checked.

How long should cold sensitivity last?

A few seconds. Pain that lingers beyond about 30 seconds or throbs afterward suggests the nerve is inflamed and may need a root canal.

Does sensitivity toothpaste actually work?

Yes, for sensitivity from exposed dentin. It blocks the tiny tubes leading to the nerve, but it takes about two weeks of twice-daily use and will not fix a cavity or crack.