1.0 fl.oz
0.5 fl.oz
Bestseller
1.7 fl.oz
#1 The Strengthening Serum
#1 The Strengthening Serum
#1 The Strengthening Serum
#1 The Strengthening Serum
#1 The Strengthening Serum
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Strengthening
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This Collection delivers a proprietary Complex of B-Group Vitamins which support immunity and barrier function.

#1 The Strengthening Serum (Formerly #1 The Serum)

This strengthening serum supports skin barrier function by harnessing Vitamin B (niacinamide), restoring radiance as it amplifies hydration. Ideal as part of your morning routine, niacinamide helps to visibly even the appearance of skin tone and improve skin clarity.

 

Use in the AM

Benefits
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Hydrates
Nourishes
Enhances radiance
Targets
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Dehydration
Blemishes and congestion
Fine lines and wrinkles
Ingredients
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Rosa Damascena (Rose) Flower Water, Niacinamide, Glycerin, Pentylene Glycol, Aloe Barbadensis (Aloe Vera) Leaf Juice, Aqua (Water), Methylpropanediol, Coco-Caprylate/Caprate, Glyceryl Stearate Citrate, Cetearyl Alcohol, Caprylyl Glycol, Olive Oil Decyl Esters, Xanthan Gum, PEG-40 Hydrogenated Castor Oil, Trideceth-9, Hydrogenated Lecithin, Cetyl Alcohol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Phenylpropanol, Santalum Spicatum (Sandalwood) Seed Oil, Citrus Aurantium Dulcis (Orange) Oil, Disodium EDTA, Glyceryl Caprylate, Squalene, Propylene Glycol, Butylene Glycol, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Citrus Limon (Lemon) Peel Oil, Litsea Cubeba Fruit Oil, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Juniperus Mexicana Oil, Pelargonium Graveolens Oil, Citrus Aurantium Amara (Bitter Orange) Flower Oil, Eugenia Caryophyllus (Clove) Leaf Oil, Sodium Hyaluronate, Ascorbyl Glucoside, Collagen Amino Acids, Polysorbate 60, Sorbitan Isostearate, Citric Acid, Ceteareth-25, Potassium Sorbate, Magnesium Aspartate, Zinc Gluconate, Brachychiton Acerifolius Flower Extract, Sodium Benzoate, Leuconostoc/Radish Root Ferment Filtrate, Leuconostoc/Radish Root Ferment Lysate Filtrate, Phospholipids, Adenosine Triphosphate, Glycosphingolipids, Behenic Acid, Ceramide NP, Cholesterol, Copper Gluconate, Ethylhexylglycerin, Phenoxyethanol, Ceramide NS, Glycine, Tocopherol, Serine, Glutamic Acid, Ceramide AP, Ceramide EOP, Ceramide EOS, Banksia Serrata Flower Extract, Citrus Australasica Fruit Extract, Davidsonia Pruriens Fruit Extract, Hibiscus Sabdariffa Flower Extract, Melaleuca Alternifolia (Tea Tree) Leaf Extract, Santalum Acuminatum Fruit Extract, Tasmannia Lanceolata Fruit Extract, Telopea Speciosissima Flower/Leaf Extract, Terminalia Ferdinandiana Fruit Extract, Aspartic Acid, Leucine, Acetyl Octapeptide-3, Caprooyl Phytosphingosine, Caprooyl Sphingosine, Alanine, Lysine, Arginine, Tyrosine, Phenylalanine, Proline, Threonine, Valine, Isoleucine, Histidine, Limonene, Citral, Citronellol, Geraniol, Linalool, Eugenol
Complimentary

Complimentary delivery on all orders.

Rosa Damascena (Rose) Flower Water, Niacinamide, Glycerin, Pentylene Glycol, Aloe Barbadensis (Aloe Vera) Leaf Juice, Aqua (Water), Methylpropanediol, Coco-Caprylate/Caprate, Glyceryl Stearate Citrate, Cetearyl Alcohol, Caprylyl Glycol, Olive Oil Decyl Esters, Xanthan Gum, PEG-40 Hydrogenated Castor Oil, Trideceth-9, Hydrogenated Lecithin, Cetyl Alcohol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Phenylpropanol, Santalum Spicatum (Sandalwood) Seed Oil, Citrus Aurantium Dulcis (Orange) Oil, Disodium EDTA, Glyceryl Caprylate, Squalene, Propylene Glycol, Butylene Glycol, Citrus Aurantium Bergamia (Bergamot) Fruit Oil, Citrus Grandis (Grapefruit) Peel Oil, Citrus Limon (Lemon) Peel Oil, Litsea Cubeba Fruit Oil, Citrus Aurantium Bergamia (Bergamot) Leaf Oil, Juniperus Mexicana Oil, Pelargonium Graveolens Oil, Citrus Aurantium Amara (Bitter Orange) Flower Oil, Eugenia Caryophyllus (Clove) Leaf Oil, Sodium Hyaluronate, Ascorbyl Glucoside, Collagen Amino Acids, Polysorbate 60, Sorbitan Isostearate, Citric Acid, Ceteareth-25, Potassium Sorbate, Magnesium Aspartate, Zinc Gluconate, Brachychiton Acerifolius Flower Extract, Sodium Benzoate, Leuconostoc/Radish Root Ferment Filtrate, Leuconostoc/Radish Root Ferment Lysate Filtrate, Phospholipids, Adenosine Triphosphate, Glycosphingolipids, Behenic Acid, Ceramide NP, Cholesterol, Copper Gluconate, Ethylhexylglycerin, Phenoxyethanol, Ceramide NS, Glycine, Tocopherol, Serine, Glutamic Acid, Ceramide AP, Ceramide EOP, Ceramide EOS, Banksia Serrata Flower Extract, Citrus Australasica Fruit Extract, Davidsonia Pruriens Fruit Extract, Hibiscus Sabdariffa Flower Extract, Melaleuca Alternifolia (Tea Tree) Leaf Extract, Santalum Acuminatum Fruit Extract, Tasmannia Lanceolata Fruit Extract, Telopea Speciosissima Flower/Leaf Extract, Terminalia Ferdinandiana Fruit Extract, Aspartic Acid, Leucine, Acetyl Octapeptide-3, Caprooyl Phytosphingosine, Caprooyl Sphingosine, Alanine, Lysine, Arginine, Tyrosine, Phenylalanine, Proline, Threonine, Valine, Isoleucine, Histidine, Limonene, Citral, Citronellol, Geraniol, Linalool, Eugenol

New Names, Same Favourite Formulations

In the coming weeks and months, you’ll begin to see a shift in how our formulations and collections are named and presented on our packaging.

This change is small, but significant—and intended to support client navigation, education, and discoverability when it comes to exploring the RATIONALE range. It’s an evolution we’re proud to be bringing you on.

Learn More

An Icon, Upsized 

To celebrate #1 The Strengthening Serum’s icon status, a special 1.7 fl.oz size has been released for a limited time, presented in gift-ready packaging.

The Ritual

Rinse your face with tepid water. Pat dry.
Dispense 2-3 drops into palm.
Smooth gently over face, neck, décolletage and backs of hands. Use as the first step of your morning ritual, for strengthened, hydrated skin.

#1 For a Reason

A non-negotiable first step in your morning ritual, this supercharged niacinamide serum targets a range of common skin concerns whilst building a strong structural foundation for stronger, hydrated, healthy-looking skin.

The Results

91%

reported improved skin hydration.

82%

saw a boost in radiance.

82%

experienced enhanced skin nourishment.

*Based on a 56-day trial with 22 participants

Active Ingredients

Niacinamide (Vitamin B3)
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A multitasking active that helps support the skin barrier, improve the appearance of uneven skin tone, enhance skin hydration, and promote a visibly smoother, more balanced complexion.

Acetyl Octapeptide-3
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A targeted peptide that helps soften the appearance of expression lines, promoting a smoother, more relaxed, and youthful-looking complexion.

Ceramides + Amino Acids
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A skin-replenishing complex that helps restore essential lipids and natural moisturising factors, supporting the skin barrier while improving skin hydration, a feeling of softness, and overall skin comfort.

Peptides
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Deliver deep hydration and strengthens skin structures to visibly firm the appearance.

An Advanced Protective Duo

This dynamic daytime duo works synergistically to support the skin’s barrier with a Vitamin B Complex, while Zinc Fusion Technology visibly evens tone and delivers solar and environmental protection. Together, these two formulations work to maintain hydration and support the skin’s natural defences against environmental aggressors.

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The Research

Healthy looking skin is supported by a natural defence system that works daily to protect and repair. This system includes the skin barrier, immune function, inflammation response, and the skin microbiome.

The outer layer of the skin helps retain moisture while defending against environmental stressors such as pollution and changing weather conditions. Immune cells work beneath the surface to detect potential irritants and help maintain balance, while inflammation plays a vital role in protection and repair when needed.

Together, these systems work in harmony to support a healthy, resilient complexion, further supported by B Vitamins.

“#1 The Strengthening Serum is my all-time favourite product. I love how it instantly calms and hydrates my skin, leaving it looking glowy and radiant.” — Jasmine

Frequently Asked Questions

How does #1 The Strengthening Serum fit into my ritual?
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#1 The Strengthening Serum is the first step in your morning ritual. Start by rinsing your skin with tepid water and pat dry. Apply 2-3 drops of #1 The Strengthening Serum before applying hydragels, crèmes and SPF.

Is #1 The Strengthening Serum suitable for all skin types?
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Yes, #1 The Strengthening Serum is suitable for all skin types.

What are the benefits of the Vitamin B Complex?
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Our B Vitamin Complex works to strengthen the skin’s barrier function. Skin appears calmer and more hydrated as redness and irritation are reduced.

What are the key active ingredients in this formulation?
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The key ingredients in #1 The Strengthening Serum include a B Vitamin Complex including niacinamide, with a combination of vitamins and peptides.

What are the key benefits of niacinamide?
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Niacinamide strengthens the skin’s barrier and enhances skin resilience. With its anti-inflammatory properties, niacinamide visibly soothes redness and brightens uneven skin tone for a healthier complexion.

Is the 0.5 fl.oz travel size a permanent offering?
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Yes, #1 The Strengthening Serum 0.5 fl.oz travel size is a permanent offering.

What is the difference between #1 The Strengthening Serum and #2 The Serum? And do I need to use both in my ritual?
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#1 The Strengthening Serum supports skin barrier defence with a B Vitamin Complex (niacinamide), while #2 The Serum defends skin from oxidative stress with a Complex of Antioxidants. It is recommended to use one formulation from #1 The Strengthening Collection and one from #2 The Brightening Collection to optimise skin health.

What is the difference between a serum and a hydragel?
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A serum is primarily water-based, offering a light consistency and quick delivery. On the other hand, hydragels, although lightweight, contain a combination of water and oil, resulting in a slower delivery in comparison.

Can this formulation be used during pregnancy and breastfeeding?
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Yes, #1 The Strengthening Serum can be used during pregnancy and breastfeeding, especially for those experiencing signs of dehydration, blemishes, and congestion. If you have any concerns or further questions about using active ingredients in skincare during pregnancy, we always recommend consulting your medical practitioner. 

Can this formulation be used during perimenopause and menopause? 
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Yes, #1 The Strengthening Serum is suitable to be incorporated into your routine. Due to niacinamide, ceramides and amino acids harnessed in this formulation, impaired and reactive skin types will experience an increase in skin nourishment and barrier function fortification, as hydration and skin suppleness is restored.