Dental floss can be used for children, but some things must be taken into account and some instructions must be followed to avoid any problems or injuries. The instructions that must be followed include:

1. Choosing the right dental floss: The dental floss must be chosen according to the child's age and mouth size, and children's dental floss that is soft and delicate can be used.

2. Supervising children: Dental floss for children must be used under the supervision of adults to avoid any injuries or problems.

3. Teaching children: Children must be taught how to use dental floss correctly, and to do so gently and without excessive pressure on the gums.

4. Taking care of the cleanliness of the floss: Care must be taken to clean the floss after use and store it in a clean, dry place, and not to reuse the same floss.

Dental floss can be used for children from approximately 4-5 years of age, but a dentist must be consulted to determine whether the child is ready to use dental floss or not, and to determine the correct and appropriate techniques for use.