How to use a vitamin C serum

Although topical vitamin C is generally well tolerated, all skin products have the potential to cause side effects.

You should always do a patch test to assess your risk of allergic reaction. Here’s how:

1. Select a small area of skin that’s easy to conceal, like your forearm.

2. Apply a small amount of product and wait 24 hours.

3. If no side effects occur, you can apply it to your face. Discontinue use if you develop a rash, redness, or hives.

When it’s time for a full application, follow the instructions on the product’s label.

It’s possible to have a skin reaction after repeat exposure, so it’s best to introduce new products one at a time, spaced out by a few weeks.

Vitamin C serum is typically applied once or twice per day. A good rule of thumb is to cleanse, tone, apply vitamin C serum, and then moisturize. Be sure to apply skin care products with clean hands.

It can be safely used with other active ingredients, although using alongside products containing niacinamide may make vitamin C less effective.