Is taking a multivitamin b complex and a vitamin C supplement unhealthy if the multivitamin also contains vitamin c?

== == No; one can safely take both supplements. However, vitamin C can cause a copper deficiency with prolonged high doses (more than 20 times the Recommended Daily Allowance (RDA) for months, for example). Unless you are taking extremely high-dose supplements, you are not likely to have this problem. Additionally, vitamin C intake levels above the RDA have not shown any additional benefit in controlled experiments. Unless there is some indication that your intake of vitamin C is deficient, it is likely that you will not benefit from the additional vitamin C supplement.