GHK-Cu + tretinoin — can I layer these or does the retinoid kill the copper?

C
Joined 2026
25 posts
3/17/2026 · 1345 views

Running tret 0.05% nightly for years. Want to add GHK-Cu to the routine. Everything I read says 'don't combine with acidic actives' but tret isn't really acidic — it's a retinoid in a pH-neutralish vehicle usually.

What's the actual interaction? Is it: (a) No problem, layer directly (b) Wait 20 minutes between (c) Alternate nights (d) Morning vs night

Current routine: cleanser, tret, wait, moisturizer. Want to slot GHK-Cu serum somewhere in there without wasting the peptide.

9 Replies

H
Joined 2025
205 posts
hexaclinicContributor
3/17/2026

The main copper-peptide-killer is low pH (vit C, AHA, BHA) because it protonates the histidine and drops the peptide's copper-binding affinity. Tret at the formulation pH (~5–6) is mostly fine. I do tret, wait 20 minutes, GHK-Cu, moisturizer. No interaction I've noticed.

Q2 stack
  • CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
  • Ipamorelin · 200 mcg · pre-bed · sub-Q
  • BPC-157 · 500 mcg · 2x/day · sub-Q
T
Joined 2025
58 posts
theoreticRegular
3/18/2026

The anxiety about 'degrading' GHK-Cu with adjacent products is overblown. If your routine isn't full of citric acid and ascorbic acid, you're fine. Tret is not the enemy here.

Longevity
  • Epithalon · 10 mg · 10d on / 80d off · sub-Q
  • MOTS-c · 5 mg · 2x/wk · sub-Q
  • 5-Amino-1MQ · 150 mg · daily · oral
P
Joined 2026
32 posts
3/18/2026

I alternate — tret Monday Wednesday Friday, GHK-Cu the other nights. Easier than timing them. Skin has been great for 6 months.

R
Joined 2025
36 posts
3/19/2026

Morning GHK-Cu, evening tret is the simplest split and the one I'd start with. Lets you see if either is causing irritation in isolation.

Current
  • Tesamorelin · 1 mg · daily AM · sub-Q
C
Joined 2026
25 posts
29d ago

Going with morning GHK, evening tret. Thanks all.

D
Joined 2025
119 posts
dr_doubtRegular
28d ago

General principle that applies here: when combining two actives with independent mechanisms, the default should be temporal separation (AM/PM split) rather than layering. Easier to isolate irritation, easier to stop one.

T
Joined 2026
8 posts
thread_saverNew Member
24d ago

Saved. Been wondering this exact question.

H
Joined 2025
205 posts
hexaclinicContributor
20d ago

@cautious_ox azelaic is pH 4–5 which is borderline. I'd either apply it separately with a real gap (30+ min) or switch GHK-Cu to the opposite time of day.

Q2 stack
  • CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
  • Ipamorelin · 200 mcg · pre-bed · sub-Q
  • BPC-157 · 500 mcg · 2x/day · sub-Q
C
Joined 2026
19 posts
20d ago

Does the GHK-Cu still work if I'm using an azelaic acid in the morning? That's low pH.

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