Black Toenails — The Trekker's Badge Nobody Warned You About
Every downhill step drives your toes into the front of your boot. Multiply by thousands of steps per day, for days — the repeated micro-trauma bleeds under the nail (subungual hematoma), turning it purple-black. It's the single most common cosmetic injury on treks, and it's largely preventable.
Why It Happens
- Boots too big or loose — foot slides forward on descents, toes smash the boot toe box repeatedly
- Nails too long — a long nail takes the impact directly; trim them SHORT before your trek
- Big descent days — Namche to Jorsale, Thorong La descent (1,600m down!), Tengboche to Namche — the big drops do the damage
- Steep downhill without poles — poles redistribute the braking force; without them your toes take it all
- Boots too small — no room for foot swelling at altitude (feet swell up to a half size)
Prevention — Before the Damage
- Trim toenails short and square — the #1 prevention; do it the night before your trek starts
- Lace for descents — re-tighten laces before big downhills; the "runner's loop" (heel lock) stops forward slide
- Buy boots a half size up — room for swelling + thick socks without crowding toes
- Trekking poles — they absorb 20–25% of downhill impact force
- Toe caps/tape — taping big toes preemptively protects against repeated impact on known descent days
When It Happens — What to Do
- Fresh bleed + pressure pain (first 24–48h): the pooled blood under the nail creates throbbing pressure — draining it gives instant relief. A sterile needle or heated paperclip through the nail releases it. Come to us if you're not confident doing this sterile — a dirty puncture turns a bruise into an infection.
- Old black nail: painless, stable — leave it. The nail will grow out over 6–12 months and eventually fall off; a new nail grows underneath
- Loose nail: don't rip it off — trim what's dead, keep it clean, let it detach naturally
- Keep trekking? — usually fine with good taping and poles; pain is the limiting factor
When It's Not Just a Bruise
- Throbbing pain + redness spreading beyond the nail — possible infection
- Nail detaching with pus or bad smell — infected nail bed
- Pain in the bone/joint itself, not just the nail — possible stress fracture
- Multiple nails affected with no trauma history — get a workup (rare but real causes exist)
Black Toenail vs. The Look-Alikes
- Subungual hematoma (the trek classic) — purple-black under the nail, throbbing pressure pain, recent downhill days; the common one
- Fungal nail — thick yellow-white crumbling nail, no acute pain, develops over months; different treatment
- Melanoma under the nail — a dark streak or patch that does NOT grow out with the nail, no trauma history; rare but must not be missed — any unexplained dark nail change deserves a look
- Nail psoriasis or other conditions — pitting, oil spots, multiple nails without trauma; needs dermatology assessment
What We Do at the Clinic
- Sterile drainage — the 2-minute procedure that relieves a fresh subungual hematoma instantly; sterile technique avoids the infection risk of field draining
- Infection treatment — cleaning, drainage of pus, antibiotics when the nail bed is infected
- Nail bed protection — dressing and splinting a partially-detached nail so it stays in place until the new nail pushes it off
- Toe fracture check — pain in the bone not just the nail gets an X-ray referral, not just tape
- Fitting advice — the lacing technique and boot check that prevents recurrence on your next trek
Common Questions
The Descent Toenail
Black toenails (subungual hematoma) — the bleeding under the nail from repetitive toe jamming into boot fronts during descents — are the classic trekking injury. The downhill pressure forces the toe against the boot; the bleeding under the nail produces the black appearance and the throbbing pain that peaks 24–48 hours after.
Treatment and Prevention
Drainage for painful tense hematoma (sterile needle through the nail — relieves pressure and pain instantly), or leave if not painful (the nail may eventually fall off but that is cosmetic). Prevention: boots sized with toe room, lace properly (heel locked so toes do not slide forward), trim nails short before the trek. The black toenail is cosmetic unless infected; the painful pressure buildup is the treatment indication.
Why They Happen
Black toenails — subungual hematoma from the toe repeatedly hitting the boot's front on descents. The cumulative impact produces the bleeding under the nail that turns it black. The boots that are too small, the downhill technique that pushes toes forward, and the inadequate nail trimming all contribute.
Prevention on the Descent
Boots sized with toe room (thumb-width from longest toe to boot front when standing on the decline), the lacing technique that locks the heel back (the runner's loop or the heel lock lacing), the trekking poles that reduce the descent impact, and the toenail trimming straight across. The toenail that hits the boot front on every downhill step is the one that blackens.
The Subungual Hematoma
Black toenail is the subungual hematoma — the blood under the nail from the repeated microtrauma of the toenail hitting the boot's toebox on the downhill descents. The pressure builds under the nail; the pain can be significant; the nail may be lost in the weeks after as the new nail grows.
The Prevention
The toenails cut short, the boots that are the right size (the toe box that does not allow the toe to hit the front on the descent), the heel lacing that locks the foot back (prevents the forward slide that produces the toe-hit), and the cushioning socks that reduce the impact. For the trek with the long descents, the toenail protection is the preparation.
The Downhill Cause
Black toenails are caused by the repeated impact — the toenail that hits the boot's front during the descent. For the trek with the long descents, the toenail bruising (the subungual hematoma) that produces the black appearance.
The Prevention
Prevention: the nail trimmed short, the boots that fit properly (the toe room that allows the foot movement without the slamming), the lacing that secures the heel (the heel lock that prevents the forward slide), and the downhill technique that reduces the toe impact.
The Prevention
Black toenail prevention: the proper shoe fit (the toe box that has the room), the nail that is trimmed short (the edge that does not impact), the descent technique that reduces the toe-loading, and the shoe lacing that secures the heel.
The Management
For the black toenail that is already present — the protection that prevents the further damage, the drainage if the pressure is painful (the sterile needle that relieves), and the awareness that the nail may be lost (the eventual shedding).
The Pressure Mechanism
Black toenail mechanism — the toe that hits the boot front on the descent (the repetitive micro-trauma that produces the bleeding under the nail). For the descent-heavy trek, the toenail that is at risk.
The Prevention
Black toenail prevention — the properly fitted boot (the size that is adequate), the lacing that secures the heel, and the technique that reduces the toe impact.
The Pressure
Black toenail pressure — the descent (the toe that hits the boot front), the ill-fitting that produces. For the black toenail, the pressure that is the cause.
The Prevention
Black toenail prevention — the properly sized boot (the toe room that is adequate), the toenail that is trimmed, and the lacing that is adjusted.
The Prevention Cost
Black toenail prevention — the toe cap ~$3-8, the proper fit (the free that prevents). For the downhill trek, the prevention that is cheap.
The Treatment
Black toenail treatment — the free (the self-resolving) or the drainage ~$10-30 (the pressure relief). For the painful, the clinic that is visited.
The Toe Cap
Black-toenail prevention — the toe cap/spacer ~$5-15 (the carried that protects). For the descent, the worn that is the cheap.
The Drainage
Toenail drainage — the ~$10-30 clinic (the relieved that is done if needed). For the pressure, the treated that is the option.
The Boot Fix
Toenail-preventing — the ~$30-100 (the fitted boot that is the cause-fix). For the downhill, the sized that is the solution.
The Drainage
Toenail drainage — the ~$10-30 (the pressure-relieved that is the clinic). For the painful, the done that is the relief.
Should I drain the blood under my black toenail myself?
Only in the first 24–48 hours and only if you can do it sterile — a heated paperclip or sterile needle through the nail releases the pressure and gives instant relief. The risk is infection from a dirty puncture or doing it on an old clotted bleed. If the throbbing is severe or you are not confident with sterile technique, we do it in 2 minutes at the clinic.
Will I lose the toenail?
Usually yes — a fully black nail is separated from the bed and will fall off over 6–12 months as a new nail grows underneath. This is not a problem; the new nail grows in normally. What you should NOT do is rip it off early — the partially-attached nail protects the nail bed. Trim loose edges, keep it clean, let nature take its course.
Is a black toenail ever dangerous?
Two versions are: spreading redness, warmth, or pus around the nail (infection tracking into the toe — needs antibiotics) and pain in the toe bone/joint rather than the nail (possible stress fracture, needs imaging). The cosmetic bruise is harmless; the infected or fractured version is not.
Can I keep trekking with black toenails?
Yes for most people — pain is the limit, and once the pressure is relieved (drained or self-resolved) most trekkers continue with good lacing and poles. The exception is infected nail bed or if the pain makes you change gait — a limping trek is a second injury waiting to happen.
Do black toenails mean my boots are wrong?
Usually yes — the classic causes are boots too loose (foot slides forward), boots too small (no room for swollen feet), or nails too long. If it happened on one trek, fix the lacing and nail length before the next. If it happens repeatedly, the boot fit itself needs review — a half-size up often solves it permanently.
