Cosrx Real Fit Vitamin C Serum C23 Review

The Cosrx Real Fit Vitamin C Serum claims to brighten skin, fade dark spots, even skin tone, plump the skin, refine texture, hydrate and smooth fine lines and wrinkles without the harsh side effects (irritation and redness) of an ascorbic acid product.

Ingredients: Propolis Extract, Ascorbic Acid, Aronia Melanocarpa Fruit Extract, Hippophae Rhamnoides Extract, Butylene Glycol, 1,2-Hexanediol, Sodium Lactate, Water, Cassia Obtusifolia Seed Extract, Sodium Hyaluronate, Allantoin

The first ingredient is 60% propolis extract, a material made by bees that soothes the skin and has antioxidant properties. Cosrx says they added propolis instead of water to combat dryness caused by vitamin C (though water is added as the eighth of 11 ingredients). Ascorbic acid is the most researched form of vitamin C in skincare, but is unstable and can be irritating. Vitamin C can even skin tone, brighten, reduce fine lines, wrinkles and spots, firm the skin and defend the skin against free radicals and environmental stressors. This formula contains 23% ascorbic acid at 99% purity. Aronia Melanocarpa Fruit Extract (black chokeberry) and Hippophae Rhamnoides Extract are antioxidants, hydrating and have some vitamins and minerals and are said to increase the stability and efficacy of the vitamin C. Butylene glycol is a skin conditioning ingredient that can soften the skin. Sodium lactate is a humectant. Cassia Obtusifolia Seed Extract is an antioxidant, anti-inflammatory and helps redness. Allantoin is a soothing ingredient.

Directions: Apply 2 or 3 drops to clean skin. Store in a dark, cool (15 to 25oC) place. If redness or irritation occurs, use every other day until skin adjusts.

The vitamin c serum comes in a lidded bottle packaged with a dropper. On opening the container, there was a small puff of air that was released and air bubbles moving the surface; this happened the first few times when opening. Cosrx sent an email saying that since the vitamin C has 99% purity, it reacts to temperature changes during shipping and gas is generated inside the product; this can cause the lid to slightly open and leak (this happened to one of my bottles). The serum comes in a 20 mL bottle and is best before 2 months once opened. It has no scent other than a slight vitamin C smell. It has a liquid texture and is light yellow in color.

I have oily/combination skin and used the Real Fit vitamin C for 5 months, using 5 to 6 drops per use (2 to 3 did not seem like enough) for 5 months every morning.

I got no irritation, stinging or redness of the skin until after about a month of use. I tried it on dry skin and damp skin with no other changes to my routine. Some days my skin would be fine, a few days my skin got very red and irritated (after 30 to 60 seconds of application) and I wanted to wash it off, and some days just stung a bit. I did not find this to be a hydrating formula (some days my skin felt quite dry and I got flakiness around my nose and mouth) and other products layered on top did not feel as nice on the skin. It left a dry, sticky layer over the skin. Using this, my skin felt a bit more rough than usual and there was no plumping of the skin.

I keep my skin care in my closet, away from light, heat and humidity. Despite this, the vitamin C was very unstable and started turning darker yellow after a couple weeks, then turning dark yellow-brown at about 6 weeks (best before 8 weeks). I did not get through more than half the bottle (of any of the bottles I purchased) before I could not use it due to oxidation. I wonder if the air in the bottle caused it to oxidize faster than it should have. Likely a bottle with about half the product and a pump would be better, but the pump would have to be metered and very smooth with a liquid formula and would probably have increased cost.

After about 2 weeks of use, my skin looked generally brighter and was less oily.

Above, after 5 months of use, my complexion looks generally brighter and less congested. The splotch of hyperpigmentation does not look greatly improved, but some of the darker spots have faded.

The left side of my face has darker hyperpigmentation and I was surprised by how much the spots on my cheekbones had faded. This is more noticeable on this side of my face likely because the spots were darker and more defined than the right side.

The left photo shows general improvement in brightness, pores and hyperpigmentation. I have some fine lines on my forehead that I do not think are improved, but the brown spots over the far eyebrow have faded and my forehead looks less oily.

I am not sure if this is my imagination or not, but looking in the mirror, I thought my skin looked darker than normal (surprising since I used this over the fall and winter). A quick read of an article on says that ascorbic acid turns into erythrulose, an ingredient in fake tanner that reacts to proteins in dead skin cells, causing darkening of the skin. This can be prevented if the ascorbic acid is used in a formula with vitamin E and ferulic acid, using an oil or cream after application of the vitamin C to protect it from the air (which I did, using The Inkey List’s Peptide Moisturizer) or using it at night.

The Cosrx Real Fit Vitamin C Serum C23 faded hyperpigmented spots, brightened and generally improved the skin’s complexion, but is not a formula I enjoyed using; it is sticky, drying, irritating, unstable, oxidized before I could get halfway through the bottle (a waste of product and money) and potentially darkened the skin. Despite the results, I would not repurchase.

Thanks for reading.

Medik8 CE-Tetra Review

Vitamin C provides antioxidant protection, protecting the skin from the damage of free radicals in the environment like UV light and pollution. Vitamin C can help reduce hyperpigmentation and red spots and maintain collagen and elasticity, thus helping wrinkles.

Depending on the form, vitamin C can be unstable and irritating. It is sensitive to heat, light and oxygen.

I have never used a vitamin C product for my skin previously and after looking at different brands and products, I bought Medik8 CE-Tetra. Medik8 is a British professional grade skincare company with roots in science and technology to manufacture effective and stable products.

The Medik8 CE-Tetra is targeted towards those with normal, dry and redness-prone skin. I have oily skin, but purchased this as the oil-free vitamin C product targeted to oily skin was more expensive.

Medik8 CE-Tetra
Medik8 CE-Tetra

This product comes in an amber glass bottle to protect it from light and dispenses from a dropper. The first ingredient, jojoba seed oil, derived from the jojoba shrub, is a source of fatty acids that the skin recognizes and can use to help the skin repair itself, defend against UV light and stimulate collagen production. It is noncomedogenic and is fast-absorbing. Next are two silicones, cyclopentasiloxane and cyclohexasiloxane. Silicones are used in skincare as conditioning and lubricating agents, providing slip and giving the skin a silky feeling. I don’t usually like using skincare with silicones; I find my skin feels heavier or extra oily when I do. However, this has been in moisturizing lotions and lotion sunscreens, which I no longer use on my face. A serum with silicones probably won’t feel as heavy. Next is the vitamin C form tetrahexyldecyl ascorbate (7%). This is a mild vitamin C derivative that is stable in light and air for up to 18 months. It is oil soluble and used in skincare for brightening, collagen production and repairing and preventing effects of environmental damage. On the box, it says that this form of vitamin C has the equivalent potency of 28% L-ascorbic acid (which is unstable). There is tocopheryl acetate (vitamin E). Vitamin E and vitamin C are used together to prevent UV damage, therefore indirectly increasing the efficacy of sunscreen. PPG-12/SMDI copolymer is a film-forming agent that has water binding properties and gives a smooth feeling to the skin. The last ingredients are grapefruit peel oil, limolene, citral and linalool. These last ingredients are generally used as aroma compounds from plants to provide fragrance – the grapefruit peel oil, limolene and citral give a citrusy scent, and linalool comes from many different plants and provides a floral scent with a bit of spice. The box says fragrance-free, so I’m assuming this means no added chemical fragrances. These plant fragrances and oils can be irritating to the skin.

I used this in the morning after cleansing and toning and used one drop for my forehead, one drop for each cheek area and one drop for the chin and jawline. When I first used this product, I was surprised by how thin it is; a water-like consistency. This made it hard to see and feel if each drop was being spread over each area. After a few days of use, though, I got used to the consistency and found the drops were being spread around. When putting this on, it absorbed immediately and made the skin feel very silky upon application (due to the silicones). It smells great; like oranges (this fragrance, though natural, is probably not necessary). After applying the serum and waiting a few minutes I only used my Colorescience Sunforgettable powdered sunscreen on top because I wanted to see how my skin reacted to the vitamin C and how it performed on its own. I usually otherwise use YBF Balance in the morning to absorb the oil on my skin throughout the day.

One-Month Results:

By the end of the first week of use I thought my skin looked a little brighter; it was very subtle. At the end of week 2 I started to get breakouts; a couple on my forehead, four small ones between my eyebrows, and a big one on the right cheek. I get breakouts every couple months, but not so many at once, and they come and go. The left side of my lower cheek breaks out every couple months and lasts a long time, and has come and gone for a long time. I have two theories about the increased breakouts during this time. My skin could have been getting used to a new product or my already oily skin does not like the extra oil from this product. Because of this, I am going to add my YBF Balance back in the morning. This is a product that absorbs oil and prevents breakouts. This product doesn’t have an effect on fine lines or hyperpigmentation, so I should still be able to see a difference in my skin with the use of Medik8 CE-Tetra.

After this one month of the Medik8 CE-Tetra use I am not seeing any difference in my fine lines or hyperpigmentation yet. Some products take time to see results. I will continue use and update in another 2 months.

Three-Months Results:

While the lighting and focus looks better, unfortunately, I’m not noticing a lot of difference after the 90 days of use – the hyperpigmentation has not faded noticeably (if at all). The fine lines on my forehead have also not diminished. I do notice that my skin does look overall brighter and feels much softer than it has in a long time. As I had noted at one months, I felt that my skin had more breakouts than usual. These have mostly calmed down other than the right side of my face where breakouts seem to occur every couple weeks to month. I’m beginning to think these are hormonal breakouts. The serum, specifically the jojoba oil, doesn’t seem to make my skin oilier than it usually is, which is something I was worried about.

Despite not noticing much difference in the fine lines and freckles while using this vitamin C serum, I am going to continue use; I still have about two-thirds of the bottle left and I think that vitamin C is very beneficial for the skin. Once I’m done the bottle I might try the vitamin C serum from Mad Hippie, it’s much less expensive and I feel like I should see more results by now from an expensive product such as this from Medik8 (of course expense doesn’t guarantee results). I am also tempted to try another vitamin C serum also from Medik8 called CE-Thione, a “step-up” from the CE-Tetra.