I take this for 4 month . It's great but one full dropper a day was a bit too much for me , it caused constipation . I lowered daily dosage to 20 droplets and its all good now . I had sleep apnea , wasn't diagnosed by a professional though , but my mouth kept opening wide when fall asleep , even during naps . It lasted for couple of years until i started this vitamin d supplement . It stopped now . And I wasn't taking anything else . Now I'm waiting for my hair to fully improve , I can see bunch of baby hair , I think its growing back . Apart from constipation I had no side effects, but its all good now after lowered dosage to 20 droplets .