I recommend that you contact Theramid directly by email (question@nichebeautylabs.com). They are very good at responding.
I asked the same question about their Copper Peptides serum. Here is the answer I received:
"As for the Copper Peptides serum, we recommend not applying it with products containing high concentrations of Vitamin C and Retinol, as it could be too strong a combination for the skin and cause irritation. If the cream is a low percentage cream, you can try using them together, although we cannot guarantee compatibility with products from other brands."
Hope this helped. 😊