Most of people are concious about taking medicines by seeing the mg level of medicines as they think that high mg of medicine can effect their body so they limit the use of medicine of high mg instead of that they ask their physicians to give them low mg medicines. So is there any effect of mg level on body?
This question is fundamentally flawed as it is based on a common misunderstanding about dosage. Every medication has a different potency, which could be thought of as the # of mg required to have a clinically noticeable effect. This ranges from a tiny fraction of 1 mg to thousands of mg.
Toxicity level similarly varies: drug A that is clinically effective at 0.075 mg daily might reach toxic levels with just 0.5 mg daily, whereas drug B that is clinically effective at 2,000 mg daily might not reach toxic levels until exceeding 4,000 mg daily. There is not a standard ratio of potency to toxicity either; it depends on multiple factors and can be looked up for each medication.
Therefore the # of mg can NOT be compared between different medications. You cannot compare whether a drug is better or worse for you based on the absolute # of mg you need to take of it.
Another way to say it is that just because you only have to take 0.075 mg of Drug A doesn't mean it is better for you than 2,000 mg of Drug B.