Q&A: Can I still use my Vitamin C serum if it turns dark orange?

Ok, this wasn’t an intended post for today but many of you commented on my IG stories and sent me DM’s about how your Vitamin C’s or specifically LAA have oxidised and can we still use them?⁠⠀
As I showed you in my IG stories my Mesoestetic Vitamin C oxidised at about 20ml or so but you need to remember that if I had been using this daily and at the right dosage then I would have used up this bottle before it oxidized. Typically a 30ml bottle would last 3months if used daily.⁠⠀
So now the question remains can you still use your vitamin C if it has been oxidised ie. it is a dark orange colour?⁠⠀
There are 2 factors to consider here:⁠⠀
1️⃣Is my Vitamin C still acting in the capacity of an anti-oxidant ie/ tacking free radicals to protect my skin from oxidative stress and/or acting in its collagen-boosting capacity?⁠⠀
2️⃣I am still going to get the brightening results with my vitamin C (especially if you are tackling hyperpigmentation).⁠⠀
Does your serum become pro-oxidant or damaging to the skin once the LAA has been oxidised? Unfortunately, there are simply not enough studies out there to show the exact impact of an oxidised Vitamin C/ LAA on the skin. There has always been an argument that Vitamin C reacts on the surface of the skin when it is exposed to air leading to pro-oxidant effect breaking down collagen however the arguments in favour of Vitamin C and its antioxidant impact seem to outweigh those against or the negative effects. Generally studies on Vitamin C/LAA “pro-antioxidant” impact are just so scarce versus the numerous studies highlighting its benefits @labmuffinbeautyscience writes a great post discussing this in detail (if you want to explore this further). Also, none of these studies talks about the skin being exposed to for example an oxidised 15% LAA formula and a detailed impact of this. ⁠⠀

I like to use Vitamin C as part of my regime to tackle hyperpigmentation for which I take a multi-pronged approach that includes a retinoid, SPF, an exfoliator to name a few. ⁠

Over the last 12 years, I have also been testing various combinations of LAA and Vitamin C derivatives. What I have noticed with “oxidised/dark orange” LAA is the “temporary staining” effect it has on the skin. Here the oxidised Vitamin C can cause a temporary darkening of the skin similar to a “tanning effect” which remains until the surface of the skin (stratum corneum) is exfoliated away. Note it does not cause hyperpigmentation but a temporary tanning of the upper surface of the skin, either way, it is not something I want from my Vitamin C (also the formula does not have to be oxidised for people to experience this darkening effect some may even notice staining with LAA no matter what condition it is in because as LAA touches the skin and is exposed to air the oxidation process begins).

What do I mean by “temporary darkening of the skin?

When Vitamin C -LAA degrades/oxides both in the bottle and on our skins it turns into dehydroascorbic acid and in turn erythrulose, this is the active component used in the tanning of the skin (alongside the popular DHA (dihydroxyacetone)- where the actives react on the skin to turn the surface layer of the skin brown.

Like tanning, this is temporary staining effect. If you find this happening to you then you might want to apply the next layer of your skincare quickly to prevent Vitamin C oxidising on your skin (with its contact to air) or you can take preventive steps to stop your bottle of Vitamin C/LAA from oxidising and lastly you can move away from LAA and use Vitamin C derivatives instead (like tetrahexyldecyl ascorbate) and others.

Again with the popularity of LAA increasing, I am hopeful we will begin to see more clinical studies addressing questions around LAA and oxidisation.
Here are some ways to prevent your Vitamin C oxidising so quickly:
1)Look for airless packaging in a LAA serum
2)Once you open a bottle of LAA use it daily until it is finished. Ie. do not open and use it irregularly, use it as quick as possible as it will begin to degrade once exposed to air.
3)Store it in a cool and dark place, like your home fridge
4)Cover it in foil to protect it from light which also degrades Vitamin C

🍊Personally: When my LAA oxidises I prefer to stop using it on my face because of its potential to stain, I am already tackling discolouration blotches and hyperpigmentation so I just don’t want to risk anything aggravating it.

Hope this helps xx