Can vitamins make you sick? And do omega 3 fish oil supplements work?

Depends. Vitamin a, e, d, and k are fat soluble and will accumulate: they have know overdoses that are toxic. B vitamins and c are water soluble - you excrete any excess in your urine. Regarding fish oils, the final data isn't known: here a reliable source: http://nccam.Nih.Gov/health/omega3.

Yes ; Yes. Sick in what way? Anything that makes some feel better may harm others. Excessive doses of vit a, d, e ; b6 can be toxic. Some vits cause stomach upset. Many react to preservatives/artificial colors found in poor-quality supplements.But a quality vit. Is unlikely to cause harm. Fish oil prevents symptoms of omega 3 deficiency, a common problem, helps inflammation ; depression: http://bit.Ly/1cpbzsb.