I thought this question was worth featuring, because it is a good example of how a seemingly easy question asking for product recommendations actually begets a much longer answer - indeed, sometimes skincare is never that simple! The reader was asking for product recommendations for retinol products. However, when including retinol in a skincare routine, I'd advise some care as retinol can interact with your other skincare products. So while people tend to focus on product recommendations, I'd also advise ensuring that the products you pair your retinol with don't inadvertently counteract each other.
Retinol and some of its variants. (Source)
I was actually mailing to ask you for a product recommendation - since you're so good with ingredients. I'm looking to add retinol to my skincare routine and was wondering if you could suggest something that's not too strong. I haven't used any before.
At the moment I have a vitamin c serum and my usual Kiehl's moisturiser. Oh and there's some salicylic acid from Hope in a Jar Night. Thanks so much!"
I don't really have all that many product recommendations for retinol (you can get prescription retinol from a doctor and it may work out cheaper in the long run, depending on where you are and your cost of healthcare), but some other non-prescription retinol products that have good reviews include Skinceuticals Retinol 1.0 and 0.5 (different strength levels, 0.5 is the weaker one), Philosophy Help Me Retinol Night Treatment, and Neutrogena Healthy Skin Anti Wrinkle Cream (not sure if it's still around or available?). There's also this product called Green Cream that a lot of people swear by. It comes in three levels, Level 3, 6, as 9 (again, differing concentrations of retinol, 3 is the weakest and 9 is the strongest). ROC also has some retinol products that from what I hear, are quite good.
Products aside, retinol can sting/irritate some people's skin, especially at the beginning, so generally if it's your first time using a retinol product, it's wise to use a lower strength retinol, and gradually work your way up to a higher strength after some time, and when your skin doesn't show any sensitivity reactions. If you've used a retinol product before, then you can judge what level would be suitable for your skin. If its your first time, you may also want to start using your retinol product maybe 2-3 times a week and then working up to daily use, just in case your skin is sensitive to it. Although most people are fine with retinol when their skin adjusts, I have come across a couple of people who can't seem to use retinol at all due to sensitivity reactions, so if anything doesn't feel right on your skin when you're trying out a low level of retinol, then trust yourself and take a break.
Also, I usually recommend that retinol be used only during the night, especially with the higher strength ones, because it may make skin more photosensitive. For that reason, some doctors also advise that if you're using retinol at night, it's also good to use a sunscreen in the day as well (which I think you're already using, so no worries there!).
Another thing to consider is that most people using retinol may find that their skin undergoes a "purging" stage. So sensitivity reactions aside, because retinol increases the rate of skin turnover, some people may find their skin getting worse (e.g. more pimples for those who are using retinol for acne), before getting better. When I used retinol I think my purging lasted a few weeks? But if you have pretty clear skin to start off with I doubt this will present a big problem for you.
Lastly, and importantly, retinol shouldn't be used with acidic products, because retinol works better with a more basic pH. You already mention that you use salicylic acid, so it's better not to use the two together. You can alternate them though, using the retinol some days and the salicylic acid on others. If you are still keen to use both, then it's best to wait 15 minutes before applying the second product, because the skin will go back to its original pH, so in theory you could combine the two with a 15 minute wait in between. I'm not sure what's in your vitamin c serum, but if your vitamin c serum is acidic too (because of the ascorbic acid), then you may also want to not use both of them together.
So that's it for my reply on retinol! In short, start off by using a lower level retinol a few times a week to get used to it, use it only at night, and don't use it with products that work best with acidic pH. You may or may not experience sensitivity and purging, so start off gradually and you can ramp up once your skin gets conditioned to the retinol. Hope this helps!