What's the right amount of vitamin c to look for in a facial cream?

Generally creams that have a higher content of ascorbic acid are more likely to be effective, especially since it tends to be unstable and not well absorbed. Others are claiming that as little as 5% - 10% ascorbic acid is sufficient. The best answer is that you should talk to a skin care professional to determine what is ideal.

This has another advantage in that they will often have products that are higher dosage and more effective than what you'll typically find in stores. If that's not an option you want to pursue, then you may have to make your decision based on trial and error. Try the highest concentrated product you can find and if you discover it irritates your skin (it is an acid after all), then switch to a weaker product.In general, you shouldn't need to worry about toxicity or overdose with Vitamin C, so start high and if you tolerate it well stay with a strong cream.