Six things. The underarms swell and are tender for days, and bumpy and numb in patches for weeks, sometimes months. In the randomised trial, 10% of treated patients had altered feeling in the skin of the upper arm that lasted about two months on average, and 5% had a blister, burn or ulcer. Nerve injury in the arm has been reported in single cases, one still severe at eight months. It needs local anaesthetic injected into each underarm. It treats the underarms and nothing else. And NICE, which reviewed it in 2017, says it should be used only with special arrangements for clinical governance, consent and audit or research, and that patients should be told about the risk of nerve damage, which we do in writing at the free consultation at Sweat Hospital, 130 Harley Street.
The usual aftermath
In the 31-adult study, 90% had swelling, 71% had bumps under the skin lasting a median of 41 days, 65% had altered sensation in the underarm skin lasting a median of 37 days, and 26% lost some underarm hair. Ice for the first day or two, loose sleeves, no vigorous exercise for about three days, and most people are at work the next day in our experience. The swelling is at its worst in the first week, and the bumps and numbness fade over the following weeks.
The rarer problems, with their figures
- Arm sensation: 8 of the 81 treated patients in the randomised trial, 10%, had altered sensation in the upper arm, lasting 67 days on average.
- Blisters, burns or ulcers on the skin: 4 of 81, 5%, lasting 28 days on average.
- Sweating more elsewhere: 2 of 81 in the randomised trial, 3%, against none with the sham.
- Nerve injury: published case reports include a thin 19-year-old whose arm strength had returned by twelve months, with reduced feeling in one fingertip and a thin 49-year-old with a lasting injury to a nerve of the arm at eight months. The manufacturer's manual warns that an underarm with little fat under the skin carries a higher nerve risk, which is why, in our clinical judgment, the fat layer is checked at the consultation.
- Infection: rare, and treated promptly.
The regulator's position
miraDry is FDA-cleared in the US for the treatment of primary axillary hyperhidrosis, for underarm hair reduction and, since 2016, with the wording that it may reduce underarm odour; it is not cleared for any other body area. In the UK, NICE guidance IPG601 of 2017 found the evidence inadequate in quantity and quality. It said the treatment should be used only with special arrangements for clinical governance, consent and audit or research, with patients told about the risk of nerve damage.
Who should not have it
Anyone with a pacemaker or another electronic implant, anyone on supplemental oxygen, and anyone who cannot have local anaesthetic with lidocaine and adrenaline. The manufacturer has not tested it in pregnancy or on the darkest skin type. The manual also discourages treatment in pregnancy and after surgery in the armpit, asks for specialist medical advice before treating anyone with a metal implant, and calls for caution with very little fat under the skin and in anyone who is immunocompromised or heals poorly. All the trials were in adults, and we treat adults.
Why people have it anyway
Because the sweating drops and stays down: 82% less sweat on average at a year in one study, 69% rated their sweating never noticeable or tolerable at a year in the randomised trial, and the improvement still there at three years in two follow-ups. The worth the money page sets out the studies, and our patients review the clinic on review.clinic, where the clinic holds 4.9 out of 5 from 82 reviews, with 100% saying it was worth it (November 2026).
Book a free consultation
Call Sweat Hospital on 0207 043 1116 or use the form below. The clinician goes through each of these with you and gives you the plan and the price in writing.
