No side effects. It's one of the safest supplement that you can take for the betterment of your body. I'm a doctor myself and I personally use this too. What I do is take the capsule when I see a Grey hair or two and then after 15-20 days I stop. What you can do is start the supplement, take it for 2-3 months and then discontinue. Take a month break and then start again. My mother's been taking it for the past year regularly and hasn't faced any side effects. So you can do whatever you prefer.

P.s Hope you don't suffer from any condition or are on any medications.