Try Lifelong — the refillable deodorant we make
Lifelong makes plastic-free, aluminium-free refillable deodorants: Vibes at £15 (ocean-bound recycled plastic case) and Luxe at £49 (anodised aluminium, lifetime guarantee). Both use compostable powder refills — no shipped water, no plastic bottles. Shop Lifelong →
What Is The Underarm Microbiome?
The underarm microbiome is the community of bacteria, fungi and yeasts that live on the skin of your armpits. It is a distinct ecosystem — warmer, moister and richer in apocrine sweat than most other skin sites — and it plays the leading role in producing the smell we call body odour. A balanced underarm microbiome is normal, healthy and largely invisible; it becomes noticeable only when certain bacterial groups dominate.
Research published on PubMed has mapped the axillary microbiome in detail, showing it is dominated by two bacterial genera: Staphylococcus and Corynebacterium. The ratio between these two is what determines how much you smell, and how your deodorant should ideally work with — not against — the skin.
What Actually Lives Under Your Arms
Sweat itself is odourless. The smell comes from skin bacteria breaking down otherwise scentless molecules in apocrine sweat into volatile compounds. The main players are:
- Staphylococcus species — associated with a milder, more acidic smell. Generally considered the "friendly" group.
- Corynebacterium species — the primary producers of the strong, pungent notes typical of body odour. They convert sweat precursors into thioalcohols, the compounds responsible for the sulphurous smell.
- Cutibacterium (formerly Propionibacterium) — present in smaller numbers, contributing to a mild vinegary note.
- Malassezia yeasts — usually harmless, occasionally implicated in itchy or irritated underarms.
A 2018 study summarised on ScienceDirect found that people whose armpits were dominated by Corynebacterium produced considerably more of these odour compounds than people whose skin favoured Staphylococcus. The bacteria are not the enemy — they are simply doing what they evolved to do.
Why The Microbiome Matters For Skin Health
Your skin barrier depends on this microbial layer. When it is disrupted — by over-scrubbing, harsh antibacterials or products that dramatically lower skin pH — you can see redness, itching, ingrown hairs and even worsening odour as opportunistic bacteria move in. The British Association of Dermatologists notes that sensitive underarm skin often reacts to fragranced or aluminium-heavy products, and that gentler formulas are usually better tolerated by people prone to irritation.
The NHS guidance on body odour is straightforward: daily washing, breathable fabrics, and a deodorant or antiperspirant that suits your skin. It does not recommend one chemistry over another, but it does highlight that irritation is a common reason people switch products.
Antiperspirants vs Deodorants — How They Affect The Microbiome Differently
This is where the two categories genuinely diverge.
Antiperspirants
Antiperspirants use aluminium salts — most commonly aluminium chlorohydrate or aluminium zirconium tetrachlorohydrex glycine — which form a temporary gel plug inside the sweat duct, reducing sweat flow. Less sweat means less food for bacteria, which reduces odour. Mainstream UK antiperspirants that list aluminium salts high on the INCI include:
- Sure Original Roll-On — Aluminium Chlorohydrate
- Dove Advanced Care Anti-Perspirant — Aluminium Zirconium Tetrachlorohydrex GLY
- Rexona (Sure) Motionsense — Aluminium Zirconium Tetrachlorohydrex GLY
- Nivea Silver Protect — Aluminium Chlorohydrate
- Mitchum Advanced Control — Aluminium Zirconium Trichlorohydrex GLY
- Sanex Dermo Extra Control — Aluminium Chlorohydrate
If you are looking to avoid aluminium — whether for skin, personal preference or simply to work with the microbiome rather than block it — these are the specific products to check the label on. Cancer Research UK is clear that there is no good evidence linking antiperspirants to breast cancer, so this is a comfort and skin question, not a safety scare.
Deodorants
Deodorants do not block sweat. They work by neutralising odour, gently shifting skin pH, or using mild ingredients to slow the growth of the specific bacteria responsible for strong smells. This approach keeps the underarm microbiome largely intact.
Supporting A Healthy Underarm Microbiome
You don't need to over-engineer this. A few habits do most of the work:
- Wash daily with a mild, fragrance-free cleanser — not an antibacterial wash unless a dermatologist has recommended one.
- Avoid scrubbing the underarms; the skin is thin and easily irritated.
- Choose breathable fabrics (cotton, linen, merino) where possible.
- Give your skin time to adjust when switching from antiperspirant to deodorant — usually 2 to 4 weeks.
- If you have persistent irritation, patch-test any new product and speak to a GP or dermatologist.
Where Lifelong Fits In
We designed Lifelong for people who want a deodorant that works with the skin rather than shutting it down. The formula is aluminium-free, plant-based, and built around arrowroot and zinc oxide — ingredients chosen for gentleness rather than aggression. The refill pouches are compostable, and the applicator itself is refillable, so you're not throwing plastic away every few weeks.
We're not going to tell you an aluminium antiperspirant is "bad" — for many people it works well and is perfectly safe. But if you'd rather leave the underarm microbiome alone and let your skin do its own thing, a well-formulated aluminium-free deodorant is a sensible place to start.
The Takeaway
Your underarm microbiome is not something to fight — it's something to understand. Odour is a by-product of specific bacteria doing their job, not a sign that anything is wrong with you. Whether you choose an antiperspirant that reduces sweat or a deodorant that supports your skin's natural ecosystem, the best product is the one your skin tolerates comfortably, day after day.
