Does toothpaste clear pimples?
The myth: a dab of toothpaste overnight dries a pimple out. What is true: the American Academy of Dermatology is blunt about it. Asked whether toothpaste is an at-home treatment for adult acne, its dermatologists say no. Toothpaste often contains abrasives such as calcium or baking soda, whitening agents such as peroxide, colour and flavour. None of these fights acne, and they can irritate or harm skin.
Irritation has a mechanism. DermNet NZ describes irritant contact dermatitis as skin injured faster than it can repair, with the oils and natural moisturising factor stripped away, and says burning and pain are more common than itch. My reading is that a tingle people take as the product working fits that description. A dried, flaky spot can look smaller for a day, which may be why the habit lasts. That is my explanation, not a trial result.
Two further points. No published trial has tested toothpaste as an acne treatment. A 2017 review of toothpaste allergy found more than 60 allergic patients in the literature, mostly with rashes around the mouth, so the ingredients are known to upset some skin.
Does lemon or limau nipis lighten dark spots?
The myth: citrus juice bleaches a dark mark, and the sour sting is the acid working. What is true: no trial shows lemon juice lightens dark marks. DermNet NZ notes that the juice has been used to bleach freckles, and also that citrus, notably lemon, is an important cause of phototoxic reactions.
Here is the mechanism. Lemon and lime contain furanocoumarins. When juice is smeared on skin and sunlight (UVA) follows, the chemicals damage the skin's cells directly. DermNet says this is not an allergy. About 24 to 48 hours later the area turns red and inflamed and often blisters, then heals over weeks and can leave a patch of darker skin that lasts for years. The condition is called phytophotodermatitis, and drip-shaped marks are typical of lime juice.
Skin of colour carries more risk. DermNet notes that the dark mark after the reaction may be more intense in skin of colour, and a 2018 report described two patients who developed sudden well-defined pigmentation after citrus contact and strong sun, with no redness first, as can happen in dark skin. In Malaysia, sunlight is rarely far away. The same acid that stings can also irritate the skin, and irritation is one way dark marks form in the first place, as the article on acne dark marks explains.
Do baking soda scrubs clean pores?
The myth: a gritty paste scrubs blackheads and oil away. What is true: the American Academy of Dermatology lists baking soda among the abrasives it warns about in toothpaste, and says scrubbing irritates skin and can make acne flare. The NHS also says not to scrub, because it can make acne worse.
There is a second problem, which is chemistry. Healthy skin is slightly acidic, with a natural surface pH of about 4.7 on average in a study of 330 volunteers. The same study found that alkaline conditions, a pH of 8 to 9, encourage the skin's resident bacteria to disperse, and that skin below pH 5 had a better barrier. Baking soda is alkaline. That study tested soaps and tap water, not baking soda, so I am reasoning from it, not quoting it. Gentle cleansers are made to avoid exactly this push.
Should I squeeze or pick a pimple?
The myth: if it has a head, get it out. What is true: the American Academy of Dermatology says popping or squeezing can push pus, dead skin cells and bacteria deeper, increasing inflammation, so acne becomes more noticeable and may scar. The NHS says the same about scarring, and the Academy adds that picking lengthens the time a pimple takes to clear and raises the risk of dark marks.
What should I do instead?
Keep the routine plain. The NHS advice is a gentle cleanser twice a day, make-up removed at night, non-comedogenic products, and salicylic acid or benzoyl peroxide, on which a pharmacist can advise. The American Academy of Dermatology names adapalene, benzoyl peroxide and salicylic acid as the proven ingredients, and says a treatment can take several weeks to a few months to show a difference, so changing products every few days works against you.
Protect the marks from the sun. The Academy advises a broad-spectrum sunscreen of SPF 30 or higher. A mark that lingers is common, and why pigmentation comes back covers the heat trigger. Lightening creams carry their own risk, covered in checking a cream for mercury.
See a doctor when acne is deep or painful, keeps coming back, or leaves scars or marks that do not fade. What a doctor checks first for adult acne sets out the questions, and the acne and pigmentation pages map the options. A pimple needs the right treatment, applied gently, for long enough.
