Why underarm shaving is different from other body areas
The underarm is structurally different from legs or the bikini line — and those differences explain why irritation is so common there.
Skin is thinner and more folded. The axilla (armpit) has thinner skin than the leg or pubic area, and natural skin folds mean the razor does not move across a flat surface. A blade pressed at the wrong angle can catch skin rather than hair.
Hair grows in multiple directions. Underarm hair does not follow a single growth pattern the way leg hair largely does (top to bottom) or pubic hair does. This means a single directional pass often misses significant coverage, tempting people into extra passes that increase friction.
Deodorant chemistry reacts with freshly-shaved skin. Deodorant and antiperspirant formulas — fragrance, alcohol, aluminium compounds — can cause significant stinging on a barrier that has just been mechanically disrupted. The NHS recommends avoiding fragranced products on freshly-shaved skin for exactly this reason.
The area is warmer and more humid. The underarm runs warmer and retains more moisture than legs or the bikini line — conditions that affect how quickly the skin surface recovers after shaving and how reactive it is to product ingredients.
What causes underarm irritation after shaving
A dull blade. The single most common cause. When a cartridge can no longer cut cleanly, it drags and compresses hair rather than slicing it — generating friction on the skin surface. The AAD identifies regular blade replacement as a primary prevention step for shaving irritation.
Shaving dry or with minimal lubrication. The underarm tends to be shaved quickly, in the shower, sometimes without a dedicated shave gel. The result: higher friction and a higher chance of the blade catching skin folds.
Pressing too hard. A sharp blade cuts on light contact. Extra pressure does not improve the shave — it increases skin-to-blade contact and raises the chance of surface irritation.
Shaving against the grain on the first pass. Against-the-grain shaving can produce a closer result, but it increases the chance of hairs being cut below the skin surface, where they can curl back and become ingrown.
Applying deodorant too quickly after shaving. The fragrance and alcohol in most deodorant products are reactive on the freshly-disrupted underarm skin barrier. This is often mistaken for razor burn — it is actually contact irritation from the product.
Multiple passes without reapplying shave gel. Each pass after the first removes the gel layer that protects the skin. Going back over an area without reapplying compounds the friction problem.
How to shave your underarms: step by step
Step 1 — Warm the skin
Two to three minutes in a warm shower before shaving softens underarm hair and relaxes the skin, making it easier for the blade to cut cleanly. Cold or dry-skin shaving increases the friction required for a clean result, which is the primary driver of underarm razor burn. The NHS includes warm-water preparation as standard guidance for minimising shaving rash.
Raising your arm and resting it behind your head while shaving stretches the skin and reduces the folds that can catch a blade.
Step 2 — Apply a fragrance-free shave gel
A shave gel creates a lubricating layer between blade and skin. For the underarm, where skin is thinner and more sensitive, fragrance-free formulas are especially important — fragranced shave products on freshly-shaved underarm skin are a common source of the stinging that gets attributed to the razor.
Apply enough gel to fully coat the area. Do not shave through a thin, near-transparent layer.
Step 3 — Start with the direction of hair growth
Underarm hair grows in multiple directions — typically downward on the upper portion and outward or at angles lower in the armpit. Begin with the direction of hair growth for each section, applying only the weight of the razor. Per the AAD's shaving guidance, the first pass should always follow the grain to minimise irritation.
For closer coverage after the initial pass, you can reapply shave gel and shave across the grain. A second against-the-grain pass should only happen on areas with full gel coverage.
Step 4 — Use minimal pressure, one section at a time
The underarm is not a flat surface. Work in sections rather than one large stroke — this lets you maintain blade angle on folded skin. Avoid pressing down; the blade should glide, not drag.
Underarm hair is coarser than leg hair and dulls cartridges faster. What still feels adequate on legs may already be past effective on the underarm. If the blade feels like it is tugging, replace it before continuing.
Step 5 — Cool rinse, then moisturiser — and wait before deodorant
Cool water helps calm the freshly-shaved skin surface. The NHS recommends applying a moisturiser after shaving to support the skin barrier. Use a fragrance-free body lotion or unscented balm.
Wait at least 20 minutes before applying deodorant. This is the most commonly skipped step that causes underarm stinging after shaving. Applying deodorant — especially spray formulas or aluminium antiperspirants — directly after shaving frequently causes a stinging or burning reaction that is uncomfortable and can extend irritation. Applying deodorant at night and shaving in the morning is a practical workaround for people with reactive underarm skin.
Ingrown hairs in the underarm area
Underarm ingrown hairs are less common than bikini-area ingrowns, but they happen — particularly if you shave against the grain and your hair tends to curl. An ingrown hair is a cut hair that re-enters the skin rather than growing outward, triggering a localised inflammatory response.
Per NHS guidance on ingrown hairs, the standard approach is:
- Warm compresses to soften the skin and encourage the hair to surface
- Avoiding squeezing or picking, which risks breaking the skin and introducing bacteria
- Not re-shaving over inflamed bumps until they have fully resolved
If you are prone to underarm ingrowns, a first-pass with-the-grain technique reduces the chance of below-surface cutting that allows hairs to curl back into the follicle.
The blade factor
More underarm irritation complaints trace back to a dull blade than to technique. The mechanism: a worn cartridge requires more pressure and more passes to achieve what a fresh blade does in one light stroke. On an area with thin, folded skin and coarser-than-leg hair, that friction is the direct cause of most surface irritation.
A blade subscription solves this structurally: instead of shaving with the same cartridge until it is visibly pulling or causing discomfort, fresh cartridges arrive on a set cadence. For underarm shaving, where hair is denser and dulls blades faster than legs, a scheduled replacement cycle prevents the gradual performance drop that causes friction-burn.
The Freya starter kit includes a 5-blade subscription razor with a refill cadence designed around this principle — fresh blades on a predictable schedule.
Further reading
- How to shave every body area: legs, underarms, bikini, pubic — the full technique matrix by zone
- Razor burn on legs: treatment and prevention — the same friction-and-barrier problem on a different body area
- How to help prevent ingrown hairs when shaving — when underarm bumps are ingrowns rather than surface irritation
This guide is informational and not a substitute for medical advice. If you experience persistent or severe skin irritation after shaving, consult a board-certified dermatologist.
Written by the Freya Editorial Team. Guidance grounded in NHS (nhs.uk) and AAD (aad.org). Last updated June 2026.
Frequently Asked Questions
How do I stop getting razor burn under my arms?
The most effective steps: soften the skin in warm water for at least two minutes before shaving, use a fragrance-free shave gel, shave with a fresh blade using minimal pressure, and wait at least 20 minutes before applying deodorant. The NHS recommends fragrance-free products on freshly-shaved skin to minimise irritation. A dull blade is the most common single cause — replacing it regularly is the highest-leverage change for most people.
Should I shave my underarms up or down?
Underarm hair grows in multiple directions, so a single-direction pass is usually insufficient for a clean result. The AAD recommends shaving in the direction of hair growth first to reduce irritation, then — if needed — across the grain on a second lathered pass. Shaving against the grain on the first pass significantly increases the chance of irritation in the underarm area.
How long after shaving underarms can I use deodorant?
Wait at least 20 minutes after shaving before applying deodorant. Freshly-shaved skin has a temporarily disrupted barrier, and deodorant ingredients — including alcohol in spray formulas and fragrance in most stick formulas — can cause significant stinging on that disrupted surface. Aluminium-based antiperspirants are particularly reactive on freshly-shaved skin. Applying deodorant at night rather than directly after a morning shave is a practical workaround for reactive skin.
Why do I get bumps after shaving my underarms?
Underarm bumps after shaving are usually either razor burn (friction-induced surface irritation from a dull blade or insufficient lubrication) or ingrown hairs (where a cut hair curls back into the skin, triggering an inflammatory response). Razor burn typically appears as flat redness that clears in one to three days. Ingrown hairs are deeper, often with a visible hair beneath the skin. Per NHS guidance, both conditions improve with gentler technique and a fresher blade.
How often should I replace my razor blade for underarm shaving?
The AAD recommends replacing razor cartridges regularly to maintain cutting efficiency and avoid irritation. For underarm shaving, where hair is coarser than leg hair and dulls cartridges faster, a general guideline is every five to seven shaves — sooner if the blade feels like it is dragging rather than gliding. A subscription refill cadence removes the habit of shaving with a cartridge past its effective life.