Dental erosion, which usually affects all the teeth in your mouth at once, “is a chemical stripping of minerals from teeth – the enamel is eaten away by acids,” says Mohamed Bassiouny, DMD, PhD, a restorative dentist and a professor at the Kornberg School of Dentistry at Temple University. Without theat protective enamel, teeth become sensitive, develop cavities and crack more easily than normal.

Bassiouny was the lead author is a case study published in the journal General Dentistry that compared the damage in the mouth of three individuals – a methamphetamine user, a cocaine user and an excessive diet-soda drinker – and concluded that each showed the same type and severity of dental erosion. In other words, excess diet-soda consumption is as bad for your mouth as meth and cocaine. What constitutes an excessive amount of soda?

The subject in the case study consumed two liters of diet soda every day for three to five years. “That sounds like a lot of soda, but I do think that women many underestimate their own consumption,” says Bassiouny. And several earlier studies found a relationship between drinking smaller amounts of soda – diet or otherwise – and dental erosion.

Since most sodas (especially colas) are corrosive because of their citric acid and phosphoric acid content, Bassiouny recommends limiting yourself to about six-12 ounce cans a week. After you indulge, rinse your mouth with water, which will dilute the acid in your mouth; salivary flow will help return acidity levels to normal. Wait about an hour to brush your teeth after a soda snack, since the abrasive scrubbing could further damage already weakened enamel. Also, drink your soda in one sitting, rather than sip it over time, so the acids have less opportunity to do damage. Another tactic: Drink through a straw placed toward the back of your mouth. You will avoid bathing your teeth in acid.