The internet is full of ways to whiten teeth at home. Some work a little, some do nothing, and some cause permanent damage. Here is the honest ranking from a hygienist.
Charcoal toothpaste: skip it
Charcoal is abrasive. It scrubs off surface stain in the short term, but it also scratches enamel, and rough enamel picks up stain faster and looks duller. Most charcoal pastes also contain no fluoride. There is no evidence it whitens the tooth itself. Dentists and hygienists consistently advise against daily use.
Baking soda and lemon: no
Baking soda is mildly abrasive and fine occasionally. Lemon juice is acid, and acid dissolves enamel. Combining them is one of the fastest ways to cause permanent sensitivity.
Whitening toothpaste: a little
Whitening toothpastes remove surface stain slightly better than regular paste. They cannot change the colour of the enamel. Choose one with fluoride and low abrasivity, and use it as your normal paste.
Whitening strips: some, with care
Strips contain real peroxide at low concentration and do lighten enamel over two weeks. The problems are uneven coverage between teeth, gel on the gums, and overuse causing sensitivity. Use them as directed, no more than one course every six months, and not on gums that bleed.
Professional whitening: the reliable option
Hygienist-applied whitening uses higher-strength gel with gum protection and desensitizer, after the teeth have been cleaned so the result is even. Custom take-home trays give the same result more gradually. Details on our teeth whitening page.
Before any whitening
Get a cleaning. Surface stain comes off with polishing, and many people find that is all they needed. Whitening on top of tartar gives blotchy results.