As a general rule, doing that is a bad idea. Human vitamins are designed specifically for people, with different dosages and ingredient concentrations. Your dog’s body processes vitamins differently than yours does, and giving them the wrong kind or amount can lead to problems.
Iron is a good example of this. Both dogs and humans need iron. However, due to differences in body weight and nutritional needs, human supplements containing iron — which are fairly common — will often contain a dosage that is toxic to your dog.
You should always consult your vet before giving your dog any new supplement or medication. They can give you advice on what your dog might need based on their age, breed, and health condition.
For your pet's health and safety, consider using supplements made specifically for dogs. There are many dog vitamins on the market that cater to their unique nutritional needs. Dog vitamins will often be in liquid or chew form as well, making them easier to feed to your dog compared to human pills.
