Antioxidant serums are easy to add to a routine, but every blend is different. Here is what an antioxidant serum can and can't do, what is in Osmosis Replenish, how to layer it with vitamin C or vitamin A, and who it suits.
What does an antioxidant serum do?
Your skin holds its own antioxidants, such as vitamins C and E, which neutralise unstable molecules (free radicals) made by sunlight and pollution. Repeated sun exposure uses them up. Pullar et al. — vitamin C and skin, 2017
An antioxidant serum applies more antioxidants to your skin. Studies on sun-aged skin are hard to read, though: most tested mixtures of ingredients, so it is unclear what each one adds, and the cream base itself moisturises. Whatever a serum adds, keeping UV off your skin remains the best protection against sun-related ageing. Pullar et al., 2017
What is in Osmosis Replenish, and who is it for?
Replenish is Osmosis's 30 mL Antioxidant Infusion Serum, made to help skin look brighter. Osmosis counts 17 antioxidants in it, carried in liposomes (tiny fat-based capsules) that it says help them reach the skin's surface layers.
The ingredient list includes niacinamide (vitamin B3), coenzyme Q10, glutathione, ergothioneine, alpha-lipoic acid, astaxanthin, a plant source of resveratrol, green tea, ginkgo, olive leaf and grape seed extracts, vitamin E and a peptide.
The box lists ageing, sensitive, irritated, oily, blemish-prone and dry skin. Worth knowing:
- Soybean oil, listed under its botanical name, Glycine soja; cosmetic labels can list food allergens this way. Allergy & Anaphylaxis Australia If you have a soy allergy, check with your doctor first.
- Denatured alcohol (alcohol denat.), fourth on the ingredient list.
- Sandalwood, grapefruit and lemon oils for scent. Fragrances are common irritants, so try it on a small area first and add one new product at a time. DermNet — Sensitive skin
What does research say about niacinamide?
Niacinamide serums are everywhere, and niacinamide is one of the better-studied ingredients. In small trials lasting 8 to 12 weeks, creams with 4 to 5% niacinamide were well tolerated, and the side of the face that got niacinamide looked smoother and less blotchy than the side given the same cream without it. Boo — niacinamide review, 2021
Osmosis doesn't say how much niacinamide Replenish contains, and none of these trials tested Replenish.
Can you use an antioxidant serum instead of retinol?
Osmosis presents Replenish as an option if you would rather not use vitamin A. That doesn't mean it does the same job. Vitamin A ingredients (retinoids) are among the most studied for sun-aged skin, mostly in the prescription form, tretinoin Mukherjee et al. — retinoids review, 2006, and we found no study comparing Replenish with a vitamin A serum.
Some people avoid vitamin A because it can cause itching, burning, redness and peeling, mostly in the first few weeks and more with prescription forms, and can make skin more sensitive to the sun. Mukherjee et al., 2006 DermNet — Topical retinoids
Prescription vitamin A creams such as tretinoin should not be used in pregnancy, and MotherSafe's factsheet does not mention retinal, so if you are pregnant, breastfeeding or planning a pregnancy, check with your doctor, pharmacist or MotherSafe before starting a retinal serum. MotherSafe — Skin care in pregnancy (PDF) We can't say whether Replenish suits pregnancy either, so ask them about it too.
How do you layer Replenish with vitamin C or vitamin A?
The box says 1–2 pumps on clean skin, morning and/or evening, followed by any Osmosis activating mist, other serums and moisturiser.
- With vitamin C: the Replenish and Catalyst boxes both allow morning use, and our Catalyst page says Catalyst layers well with Replenish. See choosing an Osmosis vitamin C serum.
- With vitamin A: vitamin A is usually applied at night DermNet — Topical retinoids, which leaves the morning for Replenish. See how to start a vitamin A serum.
In the morning, finish with sunscreen. Cancer Council recommends a broad-spectrum, water-resistant SPF 50 or 50+ sunscreen every day the UV index is forecast to reach 3 or above. Cancer Council — Preventing skin cancer Replenish has no SPF rating and is not a sunscreen; the TGA regulates products that claim sun protection as sunscreens. TGA — Sunscreens
When to see your GP or dermatologist
See your GP if you notice:
- a new spot, or a mole or freckle that changes in size, shape or colour, bleeds, itches or looks different from the others Cancer Council — Signs of skin cancer
- a red, itchy rash after starting a new product. Stop using it, and see your GP if you are worried, if it is not getting better, or if you feel unwell or have a fever Healthdirect — Contact dermatitis
Our pigmentation guide explains which colour changes need a medical check first.
What can we talk about at Melbourne Wellness?
At an advanced skin analysis appointment, we can look at your skin and routine with you and talk through where an antioxidant serum fits. If anything needs a medical opinion, we will say so.
Questions you might bring:
- What would an antioxidant serum add to the products I already use?
- Should Replenish go on in the morning, the evening or both?
- Is anything in its ingredient list likely to bother my skin?
See also our posts on vitamin C in food and skincare and skincare routine order.
