Weighing up Osmosis Catalyst vs Catalyst MD? They are two versions of the same vitamin C serum, so the choice comes down to your experience with vitamin C and whether you would like a skin consultation first. Here is how they differ, how to fit one into your morning routine with sunscreen and vitamin A, and what to realistically expect.
Osmosis Catalyst vs Catalyst MD: what is the difference?
Both are 30 mL serums built on L-ascorbic acid, which is vitamin C itself rather than a derivative. Osmosis pairs it with ketoglutaric acid, four amino acids and the minerals zinc, copper and magnesium.
- Catalyst is the version in the main Osmosis skincare range.
- Catalyst MD, from the Osmosis MD range, is the one Osmosis presents as stronger. It adds cat's claw extract, witch hazel water and a silicone, dimethicone, for a smoother feel. It also contains alcohol and should be shaken well.
Which one suits your skin?
The boxes list the same skin types for both, including dry and ageing skin, and both are made to help skin look brighter, firmer and more even. The choice is mostly about experience:
- Catalyst is the usual starting point if you are new to vitamin C serums.
- Catalyst MD suits people who already use a vitamin C serum and would like the stronger version. Skin consultation recommended.
Both serums contain a natural fragrance and grapefruit peel oil. Fragrance is a common irritant, so if your skin reacts easily, try a new serum on a small area first and introduce one new product at a time. DermNet — Sensitive skin
Should you use a vitamin C serum morning or night?
The directions on both boxes say morning and evening. If you also use a vitamin A serum, our Catalyst page suggests keeping it to a different time of day: usually vitamin C in the morning and vitamin A in the evening. Irritation often comes from several mild irritants adding up, another reason to add one active product at a time. DermNet — Sensitive skin
Prescription vitamin A creams such as tretinoin should not be used in pregnancy. If you are pregnant, breastfeeding or planning a pregnancy, check with your doctor, pharmacist or MotherSafe before starting a vitamin A serum. MotherSafe — Skin care in pregnancy
How do you use Osmosis Catalyst in your morning routine?
- Start with clean skin.
- If you use Catalyst MD, shake it well.
- Apply two pumps, or the amount you prefer.
- Add any other serum, then a moisturiser if you need one.
- Finish with an SPF 50 or 50+ broad-spectrum, water-resistant sunscreen, about a teaspoon for your face, neck and ears, 20 minutes before going outdoors. Cancer Council recommends this every day the UV index is 3 or above. Cancer Council — Sun safety
Catalyst is a serum, not a sunscreen: it has no SPF rating, and products that claim sun protection are regulated as sunscreens by the TGA. TGA — Sunscreens
Outdoors, reapply sunscreen at least every two hours and add clothing, a hat, shade and sunglasses. Cancer Council — Sun safety
What can you realistically expect?
Vitamin C is a well-known skincare ingredient, but human studies of vitamin C serums are limited and small. L-ascorbic acid breaks down easily and does not pass readily through the skin's outer layer, so the formula matters. The studies that reported visible changes used other formulas and ran for three to six months. Al-Niaimi and Chiang — topical vitamin C review, 2017
A second review called the evidence on wrinkles "less than convincing". Pullar and colleagues — vitamin C and skin review, 2017
None of these studies tested Catalyst or Catalyst MD, so they cannot tell you how either will suit your skin. If you try one, give it time and keep up your daily sunscreen.
Food is the other side of vitamin C: our post on vitamin C and skin explains where food and serums each fit.
When to see your GP or dermatologist
Some skin changes need a doctor rather than a serum. 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 — Check for signs of skin cancer
- brown patches on both cheeks, the forehead or upper lip, sometimes linked to pregnancy or hormonal contraception. This can be melasma, which needs a doctor's diagnosis, and some procedures can make it worse DermNet — Melasma
- a red, itchy or swollen rash after a new product. Stop using it, and see your GP if you are worried, if it does not settle or if you feel unwell healthdirect — Contact dermatitis
Our pigmentation guide explains what an assessment can cover.
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 which serum fits. For Catalyst MD, we recommend a skin consultation first.
Questions you might bring along:
- Which of the two suits my skin and routine?
- How do I fit vitamin C around vitamin A and sunscreen?
- Which skin changes should I show my GP?
Reviewing your whole routine for the warmer months? Our post on moving your skincare routine from winter into spring has more questions to ask.
