Scrape off any excess toothpaste with a dull knife or spoon
Rinse the stain with cold water from the back of the fabric
Apply a small amount of liquid laundry detergent or dish soap to the stain
Gently rub the fabric together or use a soft brush
Let it sit for 5 to 10 minutes
Rinse thoroughly with cold water
Repeat if needed until the stain is gone
Wash the shirt according to the care label
Check that the stain is fully removed before drying
Air-dry the shirt if any stain remains
Avoid using hot water or a dryer until the stain is gone