Look near the top of this sunscreen's ingredient list and you will find a pair of ingredients that seem to have nothing to do with each other: terephthalylidene dicamphor sulfonic acid, and arginine, an amino acid. They are there as a team. The first is Mexoryl SX, a UVA filter that is unusual because it dissolves in water rather than oil — but only once its acid groups have been neutralised, which is what the arginine does. That small piece of chemistry explains the whole character of the product. By putting one filter in the water phase and the rest in the oil phase, the formulator can reach a very high level of protection without packing all the filter weight into a greasy oil layer. The result is a sunscreen that pours almost like an essence and still carries SPF50+ and PA++++.
The oil phase holds four more filters. Ethylhexyl triazone is a remarkably efficient UVB absorber. Bis-ethylhexyloxyphenol methoxyphenyl triazine, better known as Tinosorb S, covers both UVB and UVA and helps stabilise the rest. Diethylamino hydroxybenzoyl hexyl benzoate, or Uvinul A Plus, handles the longest UVA wavelengths. And polysilicone-15, a UVB filter bound into a silicone backbone, adds to the SPF without feeling like an extra oil. All five are photostable, and none is a mineral, which is why there is no white cast at all. Butyloctyl salicylate, which appears high in the list, is not a registered filter but helps dissolve the others and boost their efficiency.
For American readers, part of the appeal is simply access. Of these five filters, Tinosorb S was added to the US over-the-counter monograph only in 2026, and Mexoryl SX is permitted solely through a single approved drug application rather than the monograph. Uvinul A Plus, ethylhexyl triazone and polysilicone-15 remain unavailable in US sunscreens, which is a big part of why Korean and European products often offer strong UVA protection in far lighter textures.
The feel lives up to the name. The lotion is thin and milky, spreads without drag and sinks in within about a minute, leaving a sheer film with a hint of dewiness. There is enough silica to take the edge off shine, so oily and combination skin should find it comfortable, though it is not a matte formula. Dry skin will be fine as long as a moisturiser goes on first; the sunscreen itself contains glycerin, panthenol and a little olive and sunflower oil but is not particularly nourishing. It layers well under makeup and can be patted over foundation for touch-ups, though no sunscreen reapplied that way delivers its full labelled protection.
Like the rest of the Melatonin Shot RX range, it is registered in Korea as a triple-function cosmetic. Niacinamide sits just after the filters, adenosine further down, and the familiar parade of hyaluronic acid forms, ceramide NP, centella, glutathione and fruit extracts brings up the rear. Most of these are too low in the list to matter much. The one worth noting is niacinamide, which adds a small, gradual tone-evening effect on top of the far bigger benefit of simply wearing sunscreen every day.
Then there is the melatonin. The official ingredient list declares it at 100 parts per million, or a hundredth of a percent. Topical melatonin has some early evidence as an antioxidant at much higher concentrations; at this level it is best thought of as a nod to the range name. The protection in this tube comes entirely from its filters, and the product would be no worse without the melatonin at all.
The one ingredient choice that genuinely weakens the formula is fragrance. The scent is light and fades quickly, but the list includes a fragrance blend, chamomile flower oil and benzyl cinnamate, a declared fragrance allergen. Sunscreen is the product people are most likely to wear every day and most likely to get into their eyes when they sweat, which is exactly where unnecessary fragrance causes problems. Rosacea-prone, eczema-prone and fragrance-allergic skin should keep looking.
As with its Tone-Up sibling, there is almost no independent user feedback yet, and a verified US price could not be confirmed. In Korea it sells for a little over thirty thousand won for 50ml, and it is available internationally through Asian e-commerce retailers, including in two-tube bundles. At a full daily dose, a tube lasts around a month.
The most important thing to say about this product has nothing to do with melatonin, hyaluronic acid or brightening. It is that the filter system is excellent — modern, photostable, broad-spectrum and cleverly distributed across the formula's two phases — and that the texture makes it easy to apply generously, which is what really determines how well any sunscreen protects. The fragrance keeps it from being a universal recommendation. For oily, combination and normal skin that tolerates scent and wants a clear, lightweight SPF50+, it is an easy one to wear every single morning, and that is the highest praise a sunscreen can earn.
