Can I take folic acid 800 mcg, biotin 5000 mcg and multivitamins together?

Yes, qualified . Folic acid is metabolized to methyl folate. In some individuals this step is inefficient and metylfolate may be a better choice. Some people have adverse reactions to high dose folic acid. Biotin is generally considered safe. This high dose would be inappropriate during pregnancy. Add one at a time and listen to your body's response.