Ever since I started putting pictures of my daily routine on Instagram I have been asked these two questions: 'Do you use different products every DAY?' and 'Don't you have to use everything from one brand in order for them to really work?'
The answers are 'Yes'. And then 'No'.
Yes, I use different skincare every day. In the same way that I wear different clothes and eat different food. And I always have. Even when wildly restricted by budget, I would have at least two moisturisers and 2/3 cleansers on rotation. Your skin is different every day. So should your products be.
No, you don't have to use everything from the same brand. The only thing to be concerned about are clashing vitamin A products that you get on prescription, but in that case, your doctor would have advised you separately about what to use/not use when issuing the prescription.
Over the counter products very rarely 'clash' because the %'s of active ingredients are low - they won't build up/interfere with each other.
What IS important is the order you use items and the formulas themselves. Your serum from XYZ won't know that your moisturiser is from ABC and stop working in protest. That's not how it works, no matter what sales hype you are given from the brands at counter.
My products, as a rule, tend to have peptides, hyaluronic acid and vitamin a (at night) in them. Varying strengths, varying formulas, similar ingredients. There are thousands of products out there. Embrace them (again, obviously within your budget).
The next time someone tells you that you simply have to use their moisturiser on top of their serum, don't buy either of them.
Or you could hold up this picture of Danny Devito below and say 'I DON'T THINK SO MATEY.'