In general, yes. Vitamin C is water-soluble and commonly used alongside magnesium without issues. Two practical considerations: (1) stomach tolerance—vitamin C can cause heartburn in some people, and magnesium can cause diarrhea at higher doses, so if taking them together feels uncomfortable, split timing. (2) dose discipline—high-dose vitamin C is not suitable for everyone, and magnesium supplements also have tolerance limits and potential side effects. If you take medications, remember magnesium may require timing separation from certain drugs. A sensible approach is moderate doses, taken with meals if needed, adjusted to individual tolerance.