The injections do; the treatment itself mostly does not. miraDry needs local anaesthetic injected into each underarm in several small injections across a grid, and the maker's manual is candid that they "will likely cause discomfort for the patient". Once the underarm is numb, in our experience most people feel pressure, warmth and suction rather than pain as each cycle draws the skin up against the cooled plate. Afterwards the underarms are sore and swollen for days, like a bruise, and tender to the touch for a week or two. The plan and the price are in writing at the free consultation at Sweat Hospital, 130 Harley Street.
The injections
A template marks a grid on each underarm, "a temporary tattoo" in the maker's words. Local anaesthetic then goes in by needle at points across the grid. This is the part you feel most. The manual requires the treatment to start at least ten minutes after the injections and never more than sixty minutes after them, so the numbing is in place before anything else happens. If needles worry you, say so at the free consultation, where the clinician goes through the injections with you.
During the treatment
The handpiece draws the underarm skin up by vacuum against a cooled plate and delivers microwave energy for a few seconds into the layer where the sweat glands sit. It then cools and releases, and moves to the next square of the grid. Up to 20 minutes per underarm, in a visit of about an hour to 90 minutes. The maker advises the lowest energy setting for a first session. We give no pain number; in our experience it is pressure, warmth and suction.
The days after
Sore and swollen like a bruise for days, tender to the touch for a week or two. In the maker-funded study of 31 adults, 90% had swelling, 87% redness and vacuum marks, and 84% discomfort. In the randomised trial, the manual's own table gives pain or soreness in 10% and numbness, tingling or sensitivity in the treated arm in 12%. In our experience ice packs wrapped in a towel, an ordinary anti-inflammatory painkiller, loose tops and no vigorous exercise for about three days see most people through, and most are at work the same or the next day. Altered sensation in the underarm skin is common for some weeks and settles, and in the randomised trial 10% had it in the upper arm. The downsides page gives every figure.
The rare serious risk
The nerves to the arm run close to the treated layer, and the manual says little or no underarm fat raises the risk of nerve injury. Case reports describe a thin 19-year-old whose strength returned at twelve months and a 49-year-old with a severe nerve injury at eight months. NICE's 2017 guidance asks clinics to tell patients about the nerve-damage risk, and in our practice the clinician goes through it with you before you consent. The full guide sets out NICE's position and the evidence it weighed.
Who should not have it
Anyone with a pacemaker or other electronic implant, on supplemental oxygen, or who cannot tolerate local anaesthetic, which is the reason this question matters. The maker discourages it in pregnancy and after underarm surgery, and advises caution in very thin patients and with poor healing. miraDry is FDA-cleared in the US for excessive underarm sweating and underarm hair, and from 2016 the label says it may reduce underarm odour. The sessions page covers whether one visit or two is likely for you.
Book a free consultation
Call Sweat Hospital on 0207 043 1116 or use the form below. The clinician scores your sweating, goes through the injections and the session with you, and gives you the plan and the price in writing. Our patients review the clinic on review.clinic, where it scores 4.9 out of 5 from 82 reviews in November 2026.
