Orange and Toothpaste Acid

The Chemistry Behind Orange Juice and Toothpaste

Have you ever heard that orange juice and toothpaste should not be mixed together? It’s an old wives’ tale that is actually rooted in science. The chemical makeup of both orange juice and toothpaste can have a dramatic reaction if combined, making it important to understand why the two should never mix. Let’s explore the chemistry behind this age-old warning.

Acids and Bases

The reason why orange juice and toothpaste shouldn’t mix lies in the difference between acids and bases. An acid is a substance that has a pH lower than 7, while a base has a pH higher than 7. Most citrus fruits are acidic, as is orange juice. To make matters more complicated, there are varying degrees of acidity or basicity depending on the type of acid or base being discussed. For example, lemon juice may have a pH of 2 while baking soda may have a pH of 8-9.

Toothpastes are also made up of acids, but with one major difference: most commercially available toothpastes contain fluoride, which is alkaline in nature. This means that when combined with an acidic substance such as orange juice (or even your stomach acid), they can create a reaction that could cause serious damage to your teeth and other parts of your body if ingested.

Reactions between Acids and Bases

When combining different acids or bases, you can expect to see different reactions occur. In some cases, the mixture will become neutralized (i.e., it will no longer be acidic or basic). In other cases, however, the reaction can be violent; this is especially true when combining acids with bases like what would happen when mixing orange juice with toothpaste containing fluoride. This reaction can result in foaming, heat generation, discoloration of materials around the reaction area (including your teeth!), etc.. So next time you reach for a glass of orange juice after brushing your teeth – think twice!


As we’ve explored here today, there’s good reason why you should avoid mixing orange juice and toothpaste together—the combination can create an acidic reaction with potentially damaging consequences if ingested or put on your teeth! It’s important to remember that this isn’t just an old wives’ tale; science proves why they shouldn’t be mixed! Understanding the chemistry behind this warning could save you from potential harm in the future – so keep it in mind next time you’re tempted to combine these two substances!

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