Last Updated on June 20, 2026 by omgbart
Fun fact: I was a fan of the Kate Somerville range back when ExfoliKate was called Kate In A Jar. Social media did not exist yet. I relied on QVC and sales pitches from the brand’s founders to learn about the latest must-haves. Years later, decades if we are being accurate, I still get the same buzz from a Kate Somerville launch that I did the first time I tried that resurfacing treatment.
The Mega-C 30% Vitamin C Brightening Mask is the brand’s in-home answer to the in-office Mega-C Radiance Facial at the Melrose Avenue clinic. It is also sold as the Mega-C Brightening Facial, in case you are searching under that name. I am all about the next best thing when it comes to pampering and results, so I could not wait to slather it all over my face. More info below.
What is it Mega-C?
The new Mega-C mask is a 20-minute rinse-off treatment that is meant to be used up to twice a week. Dubbed ‘facial in a tube,’ this launch has been formulated to address hyperpigmentation issues, ranging from sun spots to stubborn post-acne marks. It also promises to brighten and even out dull, lackluster skin.
Think of it as a quick pre-event glow booster with a long game plan. A tip from the brand founder herself: use it on the back of your hands. Brilliant.
What’s in the Kate Somerville Vitamin C mask?
Mega-C has a silicone base for one very important reason. The product contains 30% Vitamin C (in the form of Ascorbic Acid), which has to be kept anhydrous (a proper sciency word for waterless) in order to remain fresh, potent, and stable. In this way, the Vitamin C won’t oxidize and turn brown. It also ensures that each application is indeed mega brightening.
For some, Vitamin C may be too strong. To prevent any type of potential irritation, the new mask includes skin-soothing Bisabolol. This anti-inflammatory and anti-aging ingredient is derived from German Chamomile and boasts impressive hydrating benefits.
Other important botanicals on the INCI include Sea Buckthorn Oil (cell regenerating and healing), Licorice Root (soothing), Ginger Root (purifying, brightening), and Astragalus Root (stimulates circulation). Equal nods also go out to Ceramide NP and Niacinamide for their skin barrier strengthening properties.
How to use the Mega-C Vitamin C mask?
Mega-C delivers a powerful dose of potent Vitamin C to brighten the skin using the short contact therapy method. Think of it as an intense burst of Ascorbic Acid that will rapidly tackle pesky brown spots or acne marks.
There are a few rules you should follow to achieve optimal results.
- Follow directions. It’s recommended you leave Mega-C on for no longer than 20 minutes. Avoid the area around the eyes. Don’t be a hero.
- When you first try, Mega-C, commit to back-to-back applications a day or two apart to achieve the most visible results.
- Skip any acid-based resurfacing serum after rinsing off Mega-C to avoid over-treating the skin, which may lead to redness or irritation. Load up on Hyaluronic Acid instead.
- I’d probably avoid using Mega-C and ExfoliKate in the same sequence. Use one on a day you are skipping the other.
- Wear broad-spectrum SPF when introducing treatment products with a high concentration of key ingredients (in this case, Vitamin C).
User Experience
After a few uses, I found Mega-C works best for me in the morning. The texture reads like a traditional makeup primer, thanks to the silicone base. It glides on and feels a little slippery. There is no tingling.
This mask does not rinse off all that easily. I take it off with a foaming or enzyme-based powder wash in my morning shower. If you prefer to remove it sinkside, keep a hot cloth on hand. I used it twice in three days early on, and the payoff was a visibly more radiant glow.
Where to purchase:
$79 (60ml) at dermstore.com (15% off with my code OMGBART) as well as katesomerville.com, ulta.com, sephora.com
If you’re in the UK, check out SpaceNK.com or lookfantastic.com
Affiliate disclosure: This post contains affiliate links. I only recommend products I actually use and love. If you shop through these links, I may earn a small commission, which helps keep this site running.
