When taking multivitamin how to know how much mg of each you need if no doctor any sugesyions?

Would advise that you do NOT use any multivitamin preparations, as it is always best to supplement specific deficiencies. There is no evidence that multivitamins preserve excellent health. Many OTC preps, do not get absorbed or digested, and often do not provide amounts indicated on bottles. Save your money and focus on diet and exercise.

Visit this site for information about recommended daily allowance of vitamins and minerals. https://ods.od.nih.gov/HealthInformation/Dietary_Reference_Intakes.aspx For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs.

Your pharmacist can recommend a daily vitamin suitable for you. There are special multivitamins for elderly people & pregnant women. I am now more in favor of a multivitamin after reading a study showing people with cardiovascular disease who took them had improvement in cognitive function compared to a group who didn't take them.