With so many at home teeth whitening products on the market and constantly bombarding our instagram, it's hard to know what is safe and effective! Here are few ingredients you should avoid when shopping for teeth whitening solutions: CITRIC ACID According to research, citric acid can erode tooth surfaces and cause sensitivity. So applying this type gel to your teeth, particularly over an extended period of time, "is likely to cause harm," says Professor Laurence Walsh, president of the Australian Dental Association's QLD. "It is known to damage teeth when it sits in contact with them for a prolonged period of time." SODIUM CHLORITE Any teeth whitening gel that contains high levels of sodium chlorite, which can cause poisoning if ingested! "If you had a very strong solution of sodium chlorite, then that's certainly a problem," Dr Walsh says. "It's regarded as a strong oxidant, and there have been reported cases of sodium chlorite poisoning." The issue is that most teeth whitening brands do not disclose the percentages of this ingredient in their products so you have no way of really knowing if they are safe or not. HYDROGEN PEROXIDE This ingredient is often used in dental clinics under supervision with some great results. The issue with at home teeth whitening products containing hydrogen peroxide is the percentage used. Some products reviewed contained dangerous levels of hydrogen peroxide - more than 33% - highlighting the dangers that high level bleaching gels could cause, such as mouth infections, blistering and burns to gums, damage to nerves and tooth enamel, and gum-shrinking. That is why this ingredient is best left to treatments with your dentist.