# 111SKIN Y Theorem Repair Light Serum NAC Y2 for sensitive skin

**Lovi Fit: Average fit for sensitive skin.**
Normal Skin Fit: Superior · Effectiveness: Average · Safety: Excellent.

Page: https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin

The Lovi Fit is the same in every country; only the stores and prices differ, and the ones here are for Saudi Arabia.

Brand: [111SKIN](https://lovi.care/skincare/sa/brands/111skin)
Category: [Serums and treatments](https://lovi.care/skincare/sa/best/serums)

This fit is calculated for the concerns frequently associated with sensitive skin: redness, stinging, and reactions to new products. For scores based on a full skin profile (12D face scan, goals, preferences), use the Lovi app.

Works for sensitive skin; other serums fit it better.

## Why this fit

- Offers moderate benefits for your normal skin, as Glycerin and Aloe Barbadensis Extract provide hydration and soothing effects, though they are not targeted for your specific concerns of redness and irritation.
- Niacinamide and Acetyl Cysteine offer excellent skin repair by enhancing barrier resilience and reducing blemishes, which indirectly supports your skin's overall health.
- The product is safe for your sensitive skin due to the absence of harsh ingredients and the inclusion of soothing agents like Aloe Barbadensis Extract and Calendula Officinalis Extract.

## Fit by skin type

- [Oily skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/oily-skin): Average
- [Dry skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/dry-skin): Average
- [Combination skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/combination-skin): Average
- [Sensitive skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin): Average (this page)
- [Acne-prone skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/acne-prone-skin): Average
- [Skin with dark spots](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/dark-spots): Average
- [Mature skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/mature-skin): Average
- [Dry sensitive skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/dry-sensitive-skin): Average
- [Oily acne-prone skin](https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/oily-acne-prone-skin): Average

## Key ingredients

Nac Y2, Niacinamide, Calendula Officinalis Extract, Aloe Barbadensis Extract, Acetyl Cysteine

## What the research says

- A single application of a moisturizing fluid containing hyaluronic acid 1%, glycerin 5%, and Centella asiatica stem cells extract significantly increased skin hydration by 29% and reduced transepidermal water loss at 24 hours compared to baseline and an untreated control site in twenty healthy women. ([Clinical, Cosmetic and Investigational Dermatology, 2017](https://pubmed.ncbi.nlm.nih.gov/28860834/))
- Glutathione amino acid precursors effectively increase cellular glutathione levels, reducing oxidative stress, ATP depletion, and DNA damage in human keratinocytes, clinical subjects, and ex vivo skin compared to controls. ([Journal of the European Academy of Dermatology and Venereology, 2024](https://pubmed.ncbi.nlm.nih.gov/38189670/))
- Topical glutathione improves hyperpigmentation, reduces ultraviolet-induced erythema and wrinkles, decreases transepidermal water loss, and enhances antioxidant capacity. ([The Journal of Clinical and Aesthetic Dermatology, 2025](https://pubmed.ncbi.nlm.nih.gov/41416233/))
- RayGel reduced skin reaction severity with a lower average score of 93.7 compared to 123.3 for the placebo group in patients undergoing whole breast external-beam irradiation. ([American Journal of Surgery, 2005](https://pubmed.ncbi.nlm.nih.gov/15862509/))
- Topical post-laser application of human adipocyte-derived mesenchymal stem cell media combined with niacinamide significantly improved wrinkle index, melanin index, patient satisfaction, and investigator esthetic improvement scores compared to vehicle cream in patients with aging skin. ([Journal of Cosmetic Dermatology, 2021](https://pubmed.ncbi.nlm.nih.gov/33103316/))
- Topical nicotinamide prevented solar-simulated UV-induced immunosuppression in healthy volunteers, and men experienced immunosuppression at solar-simulated UV doses three times lower than those required for women. ([The Journal of Investigative Dermatology, 2008](https://pubmed.ncbi.nlm.nih.gov/17882270/))
- Topical 5% niacinamide applied twice daily for 12 weeks reduced fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin sallowness, and improved skin elasticity compared to vehicle control in 50 female white subjects with facial photoaging. ([Dermatologic Surgery, 2005](https://pubmed.ncbi.nlm.nih.gov/16029679/))
- Topical application of Calendula officinalis extract cream significantly improved skin hydration and firmness (reflected in significant changes in R0 and R6 parameters) in 21 healthy human volunteers compared to a base cream. ([Acta Poloniae Pharmaceutica, 2011](https://pubmed.ncbi.nlm.nih.gov/21928714/))
- Treatment with standardized extract of Calendula officinalis L. led to a shorter epithelization time and faster healing speed compared to mineral oil in patients with acute skin loss wounds of the hand and fingers healing by secondary intention. ([Tissue Barriers, 2022](https://pubmed.ncbi.nlm.nih.gov/34674610/))
- Topical administration of Calendula provides weak evidence of effectiveness in acute and chronic wounds compared to standard treatments based on a narrative review of available trials. ([Wounds, 2008](https://pubmed.ncbi.nlm.nih.gov/25941793/))
- A cream combining propolis, tea tree oil, and Aloe vera reduced erythema scars, acne severity index, and total lesion count better than erythromycin cream in sixty patients with mild to moderate acne vulgaris compared to placebo. ([Clinical Pharmacology, 2018](https://pubmed.ncbi.nlm.nih.gov/30588129/))
- Topical aloe vera gel significantly accelerated split-thickness skin graft donor-site healing compared to placebo in 12 patients, but showed no significant difference in pain relief. ([Plastic and Reconstructive Surgery, 2018](https://pubmed.ncbi.nlm.nih.gov/29649056/))
- Topical application of Aloe vera cream reduced postoperative pain at rest and during defecation, accelerated wound healing at two weeks, and decreased analgesic requirements in patients after open hemorrhoidectomy compared to placebo. ([Journal of Alternative and Complementary Medicine, 2010](https://pubmed.ncbi.nlm.nih.gov/20569031/))
- Topical N-acetylcysteine plus doxycycline achieved significantly greater improvements in total lesion count, inflammatory lesion count, IGA, GAGS, and CADI scores compared to benzoyl peroxide plus doxycycline in 40 patients with moderate acne vulgaris. ([Dermatology Practical & Conceptual, 2026](https://pubmed.ncbi.nlm.nih.gov/42190184/))
- Topical application of alpha-tocopherol, l-ascorbic acid, alpha-lipoic acid, glutathione ethylester, and N-acetylcysteine decreased UVB-radiation-induced cell death, apoptosis, and lipid peroxidation in ex vivo pig skin explants compared to untreated controls. ([Radiation Research, 2003](https://pubmed.ncbi.nlm.nih.gov/12537526/))
- Topical vitamin C, vitamin E, and acetylcysteine showed similar effects on the healing of experimentally created corneal wounds in rabbits, with no statistically significant differences compared to each other. ([Indian Journal of Ophthalmology, 2020](https://pubmed.ncbi.nlm.nih.gov/33229673/))

## Why other serums fit sensitive skin better

- Topical application of TAT-SOD significantly suppresses UVB-induced erythema formation, blood flow rise, and apoptotic sunburn cell formation in human volunteers compared to a vehicle control. ([European Journal of Pharmaceutics and Biopharmaceutics, 2016](https://pubmed.ncbi.nlm.nih.gov/27460952/))

## What reviewers say

Users with oily, combination, or humid-climate skin praise the serum's lightweight, water-like texture for providing deep hydration without greasiness, often noting significant improvements in redness, inflammation, and post-procedure healing. A notable portion of reviewers feel the extremely high price point is unjustified, citing strong fragrance and a lack of dramatic anti-aging results as key drawbacks compared to more affordable alternatives.

- Liked: Lightweight & fast-absorbing (mostly mentioned)
- Disliked: Extremely expensive (mostly mentioned)
- Liked: Hydrating & plumping (often mentioned)
- Liked: Soothing & healing (often mentioned)
- Liked: Good for oily skin (sometimes noted)
- Disliked: Lack of visible results (sometimes noted)
- Disliked: Strong fragrance (sometimes noted)
- Disliked: Potential irritation (rarely noted)

## How to apply

- Use your serum in the PM routine, starting 3 times a week before building up to daily use if your skin is happy.
- Apply the serum after cleansing and toning, but before putting on your moisturizer for the best results.
- Gently press 2-3 drops of the serum into your skin and wait a minute ⏱ for it to soak in.
- Since your skin is sensitive and easily irritated, apply the serum on completely dry skin to help keep it calm.
- Always do a patch test before your first use and avoid getting the serum too close to your eyes .
- Video: https://storage.pora.ai/c879dda8655a61c19d3d8c9ebad6b06d.mp4

## Questions and answers

### How well does the Y Theorem Repair Light Serum NAC Y2 work for sensitive skin?

This serum works moderately well for sensitive skin, providing soothing hydration while being safe to use, though it is not specifically targeted for redness and irritation. Treatments that fit this skin better need ingredients that directly calm redness and irritation while remaining gentle and compatible.
Sources: [Clinical, Cosmetic and Investigational Dermatology, 2017](https://pubmed.ncbi.nlm.nih.gov/28860834/)

### Which ingredients make this serum a good fit for sensitive skin?

Niacinamide, aloe, and calendula help make this serum safe and calming for sensitive skin, though a product of this type for this skin needs specialized ingredients that specifically target redness and irritation.

### What does NAC Y2 do for sensitive skin?

NAC Y2 helps calm sensitive skin by reducing irritation and protecting against everyday stressors. Because it acts as an antioxidant, it is unlikely to cause trouble and may soothe redness for a more comfortable feel.
Sources: [Indian Journal of Dermatology, Venereology and Leprology, 2018](https://pubmed.ncbi.nlm.nih.gov/30246706/), [The Journal of Dermatology, 2025](https://pubmed.ncbi.nlm.nih.gov/38923010/)

### What does Niacinamide do for sensitive skin?

Niacinamide helps calm sensitive skin by strengthening the skin barrier and reducing redness and irritation. It is very well tolerated and may improve overall comfort and resilience with regular use.
Sources: [Cutis, 2005](https://pubmed.ncbi.nlm.nih.gov/16209160/), [Journal of Cosmetic Dermatology, 2004](https://pubmed.ncbi.nlm.nih.gov/17147561/)

### Where does this serum go in a skincare routine for sensitive skin?

This treatment goes in the evening routine after toning and before moisturizing, following the simple approach for sensitive skin. Serums with actives are typically used at night for extra safety around sun exposure, though some may also be used in the morning or twice a day.

### Can I use this serum with retinol, and in what order?

You can use this treatment serum with retinol by applying the treatment after your toner and before your moisturizer in your evening routine. This serum is safe for your sensitive skin due to soothing ingredients like aloe and calendula, but sensitive skin needs calming plant extracts and barrier-strengthening ingredients to target redness and irritation effectively.

### How often should I use this serum?

You can use this serum in your evening routine. A product of this type needs soothing ingredients like aloe and glycerin, along with barrier-strengthening niacinamide, to properly calm and hydrate sensitive skin.
Sources: [Clinical, Cosmetic and Investigational Dermatology, 2017](https://pubmed.ncbi.nlm.nih.gov/28860834/)

### Can this serum clog pores, cause breakouts or purging for sensitive skin?

This serum is unlikely to cause breakouts or clog pores on sensitive skin because it is free of heavy, pore-clogging ingredients. A product of this type needs lightweight hydrators like glycerin and soothing agents like aloe and calendula to keep sensitive skin calm and clear.
Sources: [Clinical, Cosmetic and Investigational Dermatology, 2017](https://pubmed.ncbi.nlm.nih.gov/28860834/)

### Is this serum fragrance-free and alcohol-free?

It contains fragrance (benzyl alcohol and parfum) and drying alcohol (alcohol).

## Alternatives for sensitive skin

- [Paula's Choice RESIST Super Antioxidant Concentrate Serum](https://lovi.care/skincare/sa/p/paula-s-choice/resist-super-antioxidant-concentrate-serum/for/sensitive-skin) — Superior fit — SAR 461.00 at Amazon
- [SkinCeuticals C E Ferulic](https://lovi.care/skincare/sa/p/skinceuticals/c-e-ferulic/for/sensitive-skin) — High fit — SAR 865.37 at Amazon
- [Neogen Dermalogy Real Vitamin C Serum](https://lovi.care/skincare/sa/p/neogen-dermalogy/real-vitamin-c-serum/for/sensitive-skin) — High fit — SAR 130.97 at Amazon

## Pairs well with

- Cleanser: [Fresh Soy Face Cleanser](https://lovi.care/skincare/sa/p/fresh/soy-face-cleanser/for/sensitive-skin) — Superior fit — SAR 191.00 at Amazon
- Soothing Toner: [Clarins Toning Lotion with Camomile](https://lovi.care/skincare/sa/p/clarins/soothing-toning-lotion/for/sensitive-skin) — Superior fit — SAR 141.00 at Amazon
- Moisturizer with Sun Protection: [Bioderma Bioderma Photoderm Mineral SPF 50+](https://lovi.care/skincare/sa/p/bioderma/photoderm-mineral-fluide-spf50/for/sensitive-skin) — Superior fit — SAR 132.22 at Amazon

## Where to buy

- Amazon.sa: SAR 989.20 (https://www.amazon.sa/dp/B00U3CWDUK?tag=lovisa02-21&linkCode=osi&th=1&psc=1)
Prices checked 5 Nov 2026.

## Ingredients

Water, Glycerin, Alcohol, Benzyl Alcohol, Aloe Barbadensis Extract, Calendula Officinalis Extract, Carbomer, Sodium Hydroxide, Aesculus Hippocastanum Extract, Sodium Ascorbyl Phosphate, Panthenol, Niacinamide, Thiamin, Riboflavin, Pyridoxine, Cyanocobalamin, Glycyrrhiza Glabra Root Extract Licorice Root Extract, Prunus Armeniaca Kernel Oil Apricot Kernel Oil, Acetyl Cysteine, Parfum
## About the Lovi Fit

Lovi: Unbiased, science-based skincare AI trained on real user outcomes.

Lovi calculates every fit score from the full ingredient list with brand-independent rules its dermatologists and cosmetic chemists build and review, and personalizes every pick with AI trained on the real results of millions of users. Lovi trains its fit score models on a proprietary dataset built from more than 10,000 expert-labeled products and more than 100,000 simulated examples, following an internally consistent methodology presented at Cosmoprof, AMWC, and Skin of Color Update. Levels from best to worst: Superior, High, Average, Low, Caution, Warning.

Behind this fit score: Nadia Kapleva, MS (Co-founder, Medical Director); Alexey Shagraev, PhD (Co-founder, CEO and CTO); Dr. Sofía Perea Pérez, MD, MSc (Medical Board); Aishani Shah, MD (Medical Board); Asya Zubkova, MS (Medical Board); Hanna Kurets, MD (Medical Board, Medical Advisor); Elina Nazarenko, MD (Medical Board); Victoria Derkova, MS (Medical Board).

Page built Nov 8, 2026.

More from Lovi: https://lovi.care/skincare/llms.txt

## This page in other countries

- United States: https://lovi.care/skincare/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- United Kingdom: https://lovi.care/skincare/uk/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Ireland: https://lovi.care/skincare/ie/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Germany: https://lovi.care/skincare/de/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- France: https://lovi.care/skincare/fr/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Italy: https://lovi.care/skincare/it/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Netherlands: https://lovi.care/skincare/nl/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Spain: https://lovi.care/skincare/es/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Canada: https://lovi.care/skincare/ca/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Australia: https://lovi.care/skincare/au/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Singapore: https://lovi.care/skincare/sg/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin
- Saudi Arabia: https://lovi.care/skincare/sa/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin (this page)
- United Arab Emirates: https://lovi.care/skincare/ae/p/111skin/y-theorem-repair-light-serum-nac-y2/for/sensitive-skin