Osea has been earning quiet but steady applause in clean beauty circles for years, yet I still meet skincare lovers who have never tried a single one of its ocean inspired formulas. The brand’s focus on seaweed powered actives and sustainable practices makes it easy to root for their success.
Enter Seaglow Overnight Serum, a name that sounds like a mermaid’s memo to herself. Osea promises that a cocktail of 9% AHA and 2% phytic acid will send dullness packing while seaweed and Shiunko oil keep the moisture barrier happy. In brand testing nearly everyone reported smoother radiant skin within weeks so expectations are set sky high.
I spent two full weeks slotting Seaglow into my nighttime routine, resisting the urge to overuse it, to see whether the results live up to the aquatic hype and if the bottle justifies parting with hard earned cash.
This review is not paid or sponsored. All thoughts are my own and individual results will always vary because skin is personal.
What Is Seaglow Overnight Serum?
Seaglow Overnight Serum is an at home chemical exfoliant designed to work while you sleep. Products in the overnight treatment category tend to contain higher concentrations of active ingredients than daytime moisturizers because they are meant to sit undisturbed for several hours. The idea is simple: let the formula chip away at dull surface cells at night so you wake up to skin that feels fresher and looks a little brighter.
This particular serum relies on 9 percent alpha hydroxy acids blended with 2 percent phytic acid. AHAs like lactic, malic and citric acids dissolve the bonds that hold dead cells together, which can smooth texture and make tone appear more even over time. Phytic acid, an antioxidant derived from grains and legumes, offers a gentler exfoliating effect while also helping to reduce the look of enlarged pores.
Because acids can be drying, Osea pairs them with seaweed extracts and Shiunko oil. These ingredients sit on the skin’s surface to reinforce the moisture barrier and offset potential irritation. The brand recommends applying one or two pumps to clean dry skin no more than twice a week and always at night. Using sunscreen the next morning is non-negotiable since fresh-exfoliated skin is more sensitive to UV exposure.
Did It Work?
I benched my usual overnight acid mask for three whole nights before the first application which felt very scientific of me and then stuck with Seaglow for the next 14 days, applying it every third evening as the label suggests. Two pumps pressed onto clean skin, no toner, no face oil on top, just eye cream and bed.
Night one delivered a quick citrusy zing followed by a polite tingle that faded in under a minute. By morning my cheeks felt velvety but not dramatically brighter. Night four I noticed the tiniest bit of purging around my chin, nothing angry just a pair of stubborn whiteheads that cleared within a day or two. I consider that normal when swapping actives.
Heading into week two the softening effect grew more consistent. Makeup sat a touch smoother across the nose where pores usually grab foundation and the fine horizontal line on my forehead looked slightly blurred until late afternoon. On the flip side I caught a whisper of dryness along my jaw despite layering a richer moisturizer the following mornings. A single swipe of hydrating toner solved it yet it is worth mentioning if you already lean dry.
By day fourteen I could honestly tick off some of Osea’s promises: my skin felt smoother, pores appeared less obvious and overall tone had a mild refreshed look. What I did not see was the advertised radiance explosion. Friends asked if I had slept well not if I had found a new serum which sums up the level of glow boost delivered.
So yes, Seaglow worked to an extent but not enough to oust my current exfoliant. I will finish the bottle and reach for it when I want a gentle reset after travel though I will not be carving out permanent shelf space.
Main Ingredients Explained
The headline act is a 9 percent blend of alpha hydroxy acids: lactic, malic and citric. Each is water soluble so they nibble away at dead surface cells rather than diving deep into pores. Lactic acid also attracts water, which softens the sting that sometimes comes with exfoliation. Partnering them is 2 percent phytic acid, a grain derived antioxidant that offers milder exfoliation while chelating excess metal ions that can dull skin. Kept below 10 percent total, this acid cocktail sits in the sweet spot between noticeable smoothing and minimal next day irritation.
Osea’s seaweed trio—spirulina, Kappaphycus alvarezii and sea water—delivers minerals plus polysaccharides that help bind moisture on the surface. Shiunko oil, created by fermenting angelica and lithospermum roots in apricot, olive, sunflower and sweet almond oils, supplies omega fatty acids that cushion the barrier after the acids do their job. Glycerin, pullulan and pea extract add more humectant and antioxidant support while fermented pumpkin, mango and banana lend natural enzymes that amplify gentle exfoliation.
The formula is fully vegan and free of animal by-products so vegetarian users are also in the clear. Those who break out easily should note that olive fruit, sunflower seed and sweet almond oils can rank moderate on the comedogenic scale, meaning they have the potential to sit in pores and trigger congestion if you are already acne prone. Patch testing on the jawline before committing to full face use is the safest route.
As for pregnancy, most dermatologists consider low concentration AHAs acceptable yet every skin and pregnancy is unique. Because hormonal shifts can heighten sensitivity it is best to run any leave-on acid product past your healthcare provider before working it into a routine.
Fragrance is noticeably absent which makes the serum suitable for noses that twitch at essential oils. The pH sits in the mid-3 range so it stays optimally acidic for exfoliation without veering into the high-sting territory of a professional peel.
What I Liked/Didn’t Like
Here is the quick rundown after two weeks of bedtime testing.
What Works Well:
- Silky texture sinks in fast with only a mild one minute tingle
- Noticeably smoother feel by morning and softer makeup glide after a few uses
- Balanced blend of acids and cushiony oils keeps irritation low for most skin types
- No added fragrance plus vegan formula scores points for sensitive noses and ethical shoppers
- Glass bottle feels luxe and the pump dispenses a perfect dose so waste is minimal
What to Consider:
- Moisture seekers may need an extra hydrating step the next day to avoid jawline dryness
- Results lean subtle rather than transformative which might disappoint anyone chasing a wow level glow
- Olive sunflower and almond oils could be a hurdle for acne prone skin that clogs easily
My Final Thoughts
Seaglow Overnight Serum earns a respectable 7/10 in my notebook: reliable enough to keep on rotation yet not the stuff of skincare legend. It smoothed texture and tightened the appearance of pores but stopped shy of delivering the mythical mermaid glow teased in the marketing. After comparing notes with the many acid based treatments I have tried over the years I can vouch that Osea’s formula is on the gentler side which makes it a smart pick for anyone new to exfoliating serums or for those with easily ruffled skin that still wants an active kick.
If you crave glassy radiance in a single sleep or have oilier skin that laughs at mild acids you might feel underwhelmed. Similarly extremely dry complexions will likely want something creamier. For everyone in between this is a pleasant, no drama reset to reach for once or twice a week. Would I recommend it to a friend? Yes, with the above caveats and the gentle reminder that consistency matters more than a single bottle.
Should you decide Seaglow is not quite your tide pool here are a few nighttime workhorses I have rotated through my own cabinet: Nocturnal Revive Cream by Deascal is an affordable all rounder that hydrates, gently resurfaces and never seems to offend even the fussiest skin. Advanced Night Restore by Medik8 brings a peptide rich hug that pairs beautifully with retinol nights. Water Sleeping Mask by LANEIGE is my go to when travel leaves my face parched yet still craving a light finish. Finally Confidence in Your Beauty Sleep by IT Cosmetics combines moisturising ceramides with a hint of exfoliation so you wake up looking like you actually got eight hours.
Before you slather anything new on your face, do a quick patch test behind the ear or along the jawline and give it 24 hours. Apologies for sounding like an over protective parent but your future self will thank you. Remember too that the results any overnight treatment gives are temporary and require continued use to maintain so find a formula you enjoy reaching for and the glow will follow.