Baking Soda Teeth Whitening: What It Can and Cannot Do, and How to Use It Safely

Baking soda (sodium bicarbonate) is a fine, slightly gritty powder. Brushed on, it polishes stain off the outer surface of the enamel, the same job a gentle abrasive in toothpaste does. That is why teeth can look brighter after a first try, especially if the stain was from tea, coffee or paan.

It has no bleaching action. The natural colour of a tooth comes from the dentine under the enamel, and baking soda cannot touch that. It also does nothing for grey or brown discolouration inside the tooth, or for staining from medicines in childhood. The same limit applies to the toothpastes covered in our guide on whether whitening toothpastes work.

Abrasives wear. Brushing with baking soda daily, or scrubbing hard, can thin the enamel over months, which makes teeth look more yellow as the dentine shows, and more sensitive. Gums can also be irritated or cut. Enamel does not grow back.

Do not mix baking soda with lemon juice, vinegar or other acids. Acid softens enamel, and an abrasive on softened enamel strips it faster. It also stops the soda working, so you only add risk. Charcoal and salt scrubs carry the same abrasion problem.

Skip it altogether if you have sensitive teeth, receding gums, braces, exposed roots or enamel that is already worn, and do not use it on children.

Use it rarely, not as a daily routine: a small amount mixed to a paste with water, applied with a soft brush using light pressure, then rinsed well. Stop if teeth or gums become sore or more sensitive. Do not swallow large amounts, as it is salty and alkaline.

For stain you want removed properly, a dental scale and polish takes off surface stain without wearing the tooth. For a real change in shade, supervised whitening is the route, described in teeth whitening at home and the smile design page. Our guide on whether teeth whitening is safe covers the wider risks.