Toothpaste Colour Codes: What the Squares on the Tube Really Mean

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Do the Coloured Marks on Toothpaste Tubes Show the Ingredients?

Short answer: no. The small coloured rectangle printed at the sealed end of a toothpaste tube is a manufacturing mark for machines, not a code for consumers. It tells a sensor on the production line where to cut, fold or seal the packaging. Green, blue, red and black squares appear on toothpastes of every kind, and none of those colours says anything about whether the paste is "natural" or "chemical". If you want to know what is inside, the ingredients list on the tube or the box is the only reliable guide.

The myth has been circulating since at least 2013, and it still turns up regularly on Facebook, WhatsApp and short-video apps. Below we look at where it came from, what those marks really do, and how to choose a toothpaste using information that actually means something.

The viral "colour code" claim

The version most people have seen sorts toothpaste into four groups according to the colour of the stripe near the crimped end:

  • Green: said to mean all natural
  • Blue: said to mean natural ingredients plus medicine
  • Red: said to mean natural ingredients plus chemicals
  • Black: said to mean pure chemicals

It is an appealing idea because it promises a quick shortcut in the supermarket aisle: glance at the bottom of the tube, avoid the black ones, and you are done. Some versions add a warning that manufacturers deliberately hide this "secret" so shoppers will not notice.

The claim has been checked repeatedly. Snopes examined it in July 2013 and called it "completely wrong". Africa Check looked at a fresh wave of the same posts in 2021 and reached the same verdict, and Colgate itself describes the colour code as a hoax on its consumer health pages. No toothpaste brand, regulator or dental association uses such a system.

What the coloured squares really are

In the packaging industry the marks are called eye marks, colour marks or registration marks. Toothpaste tubes, like crisp packets, sachets and many cartons, start life as a long continuous strip of printed material. As that strip races through filling and sealing machines, a light sensor (the "electric eye") watches for a high-contrast block of colour. Each time the sensor spots the mark, the machine knows it has reached the right point to cut, crimp or fold the next package.

That explains why the marks look so plain. They do not need to be pretty; they need to be easy for a sensor to read against the background design. A dark mark works well on a light tube, a light or bright mark may be chosen for a dark tube, and the exact colour often depends on the artwork and the type of sensor the factory uses. Sometimes the mark ends up hidden inside a fold or trimmed away, which is why plenty of tubes do not show one at all.

So when you find two tubes of the same brand with different colour blocks, it usually means different print runs, different factories or different packaging designs. It does not mean the recipe changed.

Why "natural versus chemical" is the wrong question

Even if the colour code were real, the categories it uses would not help much. Everything in a toothpaste, including water, mint oil and baking soda, is a chemical substance. Professor Elaine Blignaut, a dental surgeon quoted by Africa Check, made exactly this point: matter is chemical whether it comes from a plant or a laboratory. Colgate notes that "medicine" in the viral posts is never defined and would most likely refer to fluoride, the ingredient dentists most want you to have.

A more useful way to look at a toothpaste is by what each ingredient does. Most pastes contain the same broad groups:

  • Abrasives such as hydrated silica, calcium carbonate or sodium bicarbonate, which polish the teeth and help lift plaque and stains. They typically make up a modest share of the paste.
  • Fluoride, usually as sodium fluoride, stannous fluoride or sodium monofluorophosphate. This is the active ingredient with the strongest evidence for preventing tooth decay.
  • Detergents, most often sodium lauryl sulfate, which create foam and help spread the paste around the mouth.
  • Humectants such as glycerol, sorbitol or xylitol, which stop the paste drying out in the tube.
  • Flavours, sweeteners, binders and colourings, which make the paste pleasant to use and keep its texture stable.

"Natural" brands often swap some of these for plant-derived alternatives, and some leave out fluoride altogether. That is a real difference worth knowing about, but you will only find it by reading the label.

How to read a toothpaste label instead

The ingredients list and the "active ingredient" line tell you far more than any coloured stripe. A few practical things to look for:

Check for fluoride and its strength

Many labels show fluoride as parts per million (ppm). Standard adult toothpastes in the United States are often around 1,000 to 1,100 ppm, while many European pastes, including those sold in the UK and Greece, contain about 1,450 ppm. Pastes below roughly 1,000 ppm are unlikely to give much protection against decay for adults.

Match the paste to the person

Children need less paste, not a different colour code. Guidance commonly recommends only a smear for children under three and a pea-sized amount after that, with an adult supervising so the child spits rather than swallows. If you are unsure which strength suits your child, ask your dentist.

Look for specific claims, then check them

Words like "sensitive", "whitening" or "enamel repair" refer to particular ingredients, such as potassium nitrate or stannous fluoride for sensitivity, or extra abrasives and peroxides for whitening. If a claim matters to you, the active ingredients line should explain what delivers it.

Watch for ingredients you personally avoid

Some people find that sodium lauryl sulfate irritates their mouth, and some prefer to avoid particular flavourings or sweeteners. The full ingredients list, not the crimp at the end of the tube, is where you will find them.

Why the myth keeps coming back

The colour-code story has a few qualities that help it spread. It takes something everyone has noticed but never thought about, gives it a hidden meaning, and offers a simple rule that feels empowering. It also taps into a wider unease about "chemicals" in everyday products, which makes a warning about black stripes feel plausible.

Similar stories exist for other packaging marks. People have claimed that the numbers on fruit stickers, the dots on bread bags or the colours on can bottoms reveal secret information. Sometimes there is a real system behind a mark, such as the price look-up codes on fruit, but the explanation is usually far more ordinary than the rumour suggests.

A good habit with any viral "secret code" is to ask who would be using it. A colour key that manufacturers supposedly use to label their own products, but never publish, never mention and never apply consistently, is not a code at all.

The practical takeaway

You can ignore the colour block at the end of the tube. Choose a toothpaste by reading the ingredients, make sure it contains fluoride at a sensible strength unless your dentist has advised otherwise, and use the right amount for the person brushing. If you have concerns about a particular ingredient, sensitivity or an allergy, talk to a dentist or doctor.

Brushing twice a day with a fluoride toothpaste, cleaning between the teeth and having regular dental check-ups will do far more for your teeth than any stripe on the packaging.

Sources: Snopes: Toothpaste colour code claim (2013); Africa Check: Colour-coded blocks don't indicate your toothpaste's ingredients; Colgate: What is a toothpaste color code?; Wikipedia: Toothpaste; earlier coverage by Higher Perspective.

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