What are the health benefits of taking a generic multivitamin? And are there any side effects?

It is fine to take. If a person has knowledge of nutrition and has a very balanced diet, then he or she may not need to take a daily multivitamin because his foods contain enough. I recommend each person take a multivitamin because many people don't have a truly balanced diet. Some people also need extra vitamin d, calcium, folate, omega3, etc..., depending on individual issues. Generally, there are no side effects.