If you happen to swallow just a little bit of toothpaste then nothing bad will happen and there's nothing you really need to do.
Swallowing a small amount of toothpaste is not harmful but it may cause some stomach pain.
Just drink some water to help flush the toothpaste on down your throat and into your stomach and after a few hours or at least within 24 hours the toothpaste will leave your stomach.
If you swallow more than the normal amount of toothpaste for brushing your teeth then contact poison control or go to urgent care.
If a toddler or young child swallows a lot of toothpaste then take them to the hospital because they may need to have their stomach pumped.
But if the child just swallowed a small amount of toothpaste then they will be okay.