Peptide skincare works best when the peptide is matched to a stable base: a suitable pH, gentle processing temperatures, compatible actives and a preservative system that does not break the peptide down. For NZ and Australian indie brands, formulation and claims wording matter as much as the peptide itself. The INCI Lab develops peptide serums and creams from a 100-unit MOQ with full IP transfer.
Peptides are one of the most requested actives we hear about from founders, and also one of the easiest to get wrong. A peptide on an ingredient list does not make a product perform. This guide explains what a cosmetic chemist checks before a peptide formula goes anywhere near a production batch.
What are peptides in skincare, and why do indie brands want them?
Peptides are short chains of amino acids. In cosmetics they are generally used as signalling or carrier ingredients, and they are popular because consumers associate them with firmer-looking, smoother-looking skin. For an indie brand they offer a story that is easy to explain and a premium price point, but the evidence varies a great deal between individual peptides. Part of our job is helping you choose ones with credible supplier data rather than whatever is trending.
What do peptides need to stay stable in a formula?
Peptides are sensitive molecules, so the base matters. We look at four things:
- pH. Each peptide has a preferred pH window, set by its supplier. Many sit in a mildly acidic to neutral range, which is another reason a peptide and a low-pH acid do not automatically belong in the same bottle.
- Temperature. Most peptides are added in the cool-down phase, not into the hot water or oil phase, to avoid heat degradation.
- Water activity and hydrolysis. Water-rich serums can let peptides break down over time, which is why accelerated and real-time stability testing is not optional.
- Chelators and antioxidants. Trace metals and oxidation can degrade both the peptide and the base, so protective ingredients are part of the design.
Can you combine peptides with vitamin C, acids or retinol?
Sometimes, but not casually. Copper peptides such as GHK-Cu are widely discussed as a poor match for low-pH L-ascorbic acid, and many formulators keep them in separate products or separate routine steps. Strong exfoliating acids can also push the pH outside a peptide's comfortable range. Rather than stacking everything into one formula, we often recommend a focused peptide serum and a separate vitamin C product. See our guides to vitamin C serum formulation and retinol formulation.
How do you test that a peptide formula actually holds up?
Three layers: stability testing at different temperatures and light conditions, preservative efficacy (challenge) testing, and packaging compatibility. Airless pumps and opaque or UV-protective packs are common choices for peptide serums because they limit air and light exposure. Preservative efficacy testing is NZ$1,200 per formula at The INCI Lab, and it should be done on the final formula in its final pack. Read more on stability testing and preservative efficacy testing.
What can you claim about peptides in NZ and Australia?
Keep claims cosmetic and appearance-based: language such as "helps skin look smoother" or "visibly improves the look of fine lines" sits in a different category from claims about changing skin structure or treating a condition. Comparisons to injectables or "Botox-like" language invite regulatory and consumer-trust problems, and you should be able to substantiate every claim with supplier data, your own testing or both. Our claims guide covers the detail. In Australia, ingredients must also be covered under AICIS requirements, and we help you check this alongside NZ, EU and US requirements as part of the compliance stage.
Which INCI Lab pathway suits a peptide product?
It depends on how custom you want to go. Ready-to-Go bases are pre-formulated and stability-tested, with MOQs starting from 100 units. The Accelerator (4-6 months, from NZ$2,000-$5,000) adapts a proven base to your chosen actives. The Visionary (9-12 months, from NZ$4,000) is bespoke from scratch with full IP transferred to you. Not sure which fits? A 30-minute Ask The Chemist consult is NZ$150. All routes can be vegan, cruelty-free and fragrance-free.
Frequently asked questions
Do peptide serums need a special preservative?
They need one that is effective in the formula's pH range and compatible with the peptide. This is confirmed through preservative efficacy testing on the final formula, not assumed.
Can I make a vegan, cruelty-free peptide serum?
Yes. Many peptides are made synthetically, but sourcing varies, so we check supplier documentation for vegan and cruelty-free status before specifying them.
What is the minimum order for a peptide product?
Minimums start from 100 units on Ready-to-Go bases and typically range up to 500 units on custom routes.
Can I sell a peptide product in Australia if I am based in NZ?
Generally yes, provided the product is compliant with Australian requirements, including AICIS obligations for ingredients and correct labelling and claims. We can guide you through this.
Should peptides and vitamin C be in the same product?
Usually not, particularly with copper peptides and low-pH L-ascorbic acid. Separate products are the safer starting point.
Will I own the formula?
On The Visionary pathway, full IP transfers to you before manufacturing. The Accelerator gives you ownership of the finished SKU.
Ready to talk peptides? Get in touch to start your project.