A: It is safe and desirable to use toothpaste with fluoride as soon as possible. One of the criteria is that your child can understand the need to spit out excess toothpaste and not swallow it. If you use a minimal amount (less that ¼ to ½ of a pea size), you are probably safe. We do not want our children swallowing toothpaste because if children swallow too much fluoride on a regular basis, it can cause permanent staining of their permanent teeth, which are developing in their jaws from birth until 12 years old.