Are pure vitamin C ampoules effective?

My skin is red because I've been suffering from folliculitis,

I was recommended to try applying a Vitamin C ampoule.

So I looked for pure vitamin products and found Nano Recipe's Pure Vitamin Ampoule. But then I wondered if vitamin ampoules might irritate sensitive skin even more.

I'm a bit worried. I'm thinking of trying it if it works well. What do you think?

Please recommend some other products that are effective.