Deworming can be done both internally and externally on cats at the same time. However, for kittens under 2 months old, it is best not to deworm internally and externally at the same time, as this will affect its health. It is safer to do it about a week apart. Kittens should be dewormed internally and externally once a month, and adult cats should be dewormed internally and externally every three months.
Notes on deworming cats:
1. If the owner is going to bathe the cat, he needs to deworm the cat three days after bathing.

2. If the cat is sick or has a weak constitution, it is best to wait for the cat to recover before deworming.
3. Vaccination and deworming cannot be performed at the same time. Cats should be dewormed one week after vaccination.

4. Breastfeeding cats cannot be dewormed, but can be dewormed within 2-4 weeks after the end of the lactation period.