Nicotine and dark nail polishes can stain your nails yellow and are common causes of unsightly discoloration. You can also get yellow nail stains from exposing your nails to rust, paints, varnishes and other chemicals, and from fungal infections. Routine nail hygiene and home stain removal methods are usually effective at removing discoloration to give you healthy and beautiful nails.

Scrub your nails with a nail brush and warm soapy water. Use a cleanser that contains tea tree oil if you suspect a fungal infection. Clean under the nails using a nail stick. Rinse off soap with clean, warm water.

Combine equal amounts of warm water and 3 percent hydrogen peroxide in a small bowl for fingernails or in a large dish tub for toenails.

Soak nails in the hydrogen peroxide solution for five minutes. After five minutes, scrub your nails with an old toothbrush.

Rinse your nails in warm water to remove the hydrogen peroxide mixture.

Remove remaining yellow stains by scrubbing your nails with a toothbrush and whitening toothpaste or a baking soda paste. To make the baking soda paste, combine equal amounts of baking soda and warm water.

Rinse your nails with warm water and pat them dry using a clean towel.

Treat nail fungus by applying an over-the-counter antifungal nail medication to the nails, following the medication's manufacturer label directions. Alternatively, as a natural home remedy, rub tea tree oil into the affected nails once a day until the fungal infection is gone. Although tea tree oil is not accepted as a nail fungal treatment by the medical community, laboratory tests show it is effective at killing a wide variety of fungi, according to a report in the "Journal of Applied Microbiology."

Seek treatment from a licensed medical professional if home treatment does not successfully remove yellow nail stains. Fungal infections resistant to home treatment require prescription-strength medications.