Personal care · lesson 9 of 10
Body care, deodorant & fragrance
Moisturize smart, exfoliate less than you think, and know what your deodorant and perfume actually do.
7 min read · reviewed October 2026
Dry skin: draw water in, then seal it
Moisturizers work through three kinds of ingredients:
- Humectants draw water into the skin — glycerin, urea, hyaluronic acid, lactic acid.
- Emollients smooth the rough gaps between skin cells — plant oils, squalane, fatty alcohols.
- Occlusives form a film that slows water loss — petrolatum, dimethicone, mineral oil, shea butter. Petrolatum is among the most effective, and allergy to it is very rare.
Apply within a few minutes of bathing, on damp skin. Keep showers short and warm rather than hot. For thick, rough skin on heels and elbows, urea at higher strengths softens and loosens the buildup.
Exfoliation has a ceiling
Skin sheds on its own. Occasional gentle exfoliation smooths rough patches — and chemical exfoliants such as lactic acid or urea are often gentler than gritty scrubs. But daily scrubbing, stiff brushes and stacked acids break down the barrier and cause dryness, redness and itching. A couple of times a week is a sensible ceiling for most people; for sensitive or eczema-prone skin, often none at all.
Deodorant vs antiperspirant
A cosmetic. It doesn't reduce sweat — it masks odor and uses antimicrobials, alcohol or fragrance to curb the skin bacteria that break sweat down into smelly compounds.
An OTC drug in the US. Aluminum salts form temporary plugs in sweat ducts, and the product has to prove in testing that it reduces sweat. Many products are both deodorant and antiperspirant.
Antiperspirant works best on dry skin at bedtime, when sweat glands are quieter and the plugs have time to form. It keeps working after a morning shower.
Fresh sweat is nearly odorless. Odor comes from bacteria such as Corynebacterium breaking down compounds in underarm sweat. A variant of the ABCC11 gene, common in East Asian populations, sharply reduces underarm odor — and also produces dry earwax.
There's no evidence your armpits need to 'detox' when you switch. Baking-soda deodorants are alkaline and can irritate underarm skin.
To be labeled 'extra effective', how much must a US antiperspirant reduce sweating in standardized testing?
Somewhere between 0 and 100 %.
Reveal the answer →
At least 30% (20% for standard claims)
Under FDA's antiperspirant rules, a standard product must cut sweat by at least 20%, and an 'extra effective' one by at least 30%. So even a good antiperspirant reduces sweat rather than stopping it — which is why truly heavy sweating needs a clinician, not a stronger stick.
Fragrance: pleasant, and a leading allergen
Fragrance is one of the most common causes of allergic skin reactions to cosmetics. Allergy develops after repeated exposure — often years of trouble-free use — and once it develops it's usually lifelong.
- Natural isn't safer. Essential oils such as lavender, tea tree, citrus and ylang-ylang contain the same allergens, and some components (linalool, limonene) become more allergenic as they oxidize in air.
- Citrus oils plus sun can cause a reaction: bergamot oil can leave streaky brown marks where perfume was sprayed on sun-exposed skin.
- Leave-on matters more than rinse-off. Choose fragrance-free lotions first if you're sensitive; a scented body wash is on your skin for a minute.
- Spray on clothes, not skin, if you love a perfume but react to it (test fabric first for staining).
You switch to an 'all-natural' deodorant with essential oils and baking soda, and your underarms turn red and itchy. What's the likely cause?
- Your body 'detoxing' from aluminum
- Irritation from the alkaline baking soda, or an allergy to fragrance compounds in the essential oils
- Not applying enough product
- Sweat trapped by leftover aluminum
Show the answer →
B.Irritation from the alkaline baking soda, or an allergy to fragrance compounds in the essential oils
Baking soda's high pH is a common irritant for thin underarm skin, and essential oils are fragrance allergens like any other. 'Detox' isn't a real process here. Switch to a fragrance-free, baking-soda-free product; if the rash persists or spreads, see a clinician.
Compare moisturizers by their humectants and occlusives, check whether a 'deodorant' is actually an antiperspirant (in the US it will carry a Drug Facts panel), and look for fragrance-free options if your skin reacts easily.