Narrowband And Broadband UVB Improved Eczema About Equally. Only One Arm Lost Patients To Side Effects.
Narrowband UVB replaced broadband UVB in dermatology more than twenty years ago, and the switch happened without anyone running a head-to-head trial in eczema. A Cochrane review said this in 2021: not one of the randomized trials it found had compared the two. A Canadian team has now run that comparison, and the answer is more useful than a simple win for either lamp.
Over 12 weeks, the two wavelengths improved eczema by about the same amount. The difference between them showed up somewhere else entirely, in who was still coming to treatment at the end.
What The Trial Did
Aaron Drucker’s group randomized 69 adults with moderate-to-severe atopic dermatitis at two hospital phototherapy units, one in Toronto and one in Vancouver. Thirty-four went to full-body broadband UVB (290 to 320 nm) and 35 to narrowband UVB (311 to 313 nm). Everyone was asked to come three times a week for 12 weeks, and patients kept using topical treatment as their own dermatologist saw fit. Sixty-six were included in the main analysis.
The primary measure was the change in EASI, the standard severity score for eczema.
What They Found
Broadband UVB brought EASI down by 8.1 points (95% credible interval 12.1 to 4.1). Narrowband brought it down by 8.9 points (95% credible interval 13.0 to 4.9). The adjusted difference between the two was 0.7 points in narrowband’s favor, with a credible interval running from 5.6 points better to 4.1 points worse.
That interval is the finding. It comfortably contains zero, so this trial does not show narrowband is more effective for eczema. The authors put the probability that narrowband is better at 60.3%.
Every secondary outcome told the same story. Roughly a quarter of patients in each arm reached treatment success on the validated physician assessment, 25% on broadband and 26.5% on narrowband. Patient-reported eczema severity, itch, quality of life, and eczema control all moved by similar amounts in both groups.
Where The Treatments Differed
Redness was common in both groups and more common on broadband, affecting 59% of broadband patients and 47% of narrowband patients.
But the number that stands out is withdrawals. Four of the 32 broadband patients stopped treatment because of adverse events, two because their eczema got worse and two because of skin reactions to the phototherapy itself. In the narrowband arm, that number was zero.
Read that carefully, because it is easy to oversell. Four events against none is a small difference in absolute terms, the trial was not designed to test it, and with numbers this size it could shift with a handful of additional patients. It is a signal about tolerability, not a proven safety margin. What it does is line up with the clinical impression that pushed dermatology toward narrowband in the first place, and it is the first time that impression has been observed in a randomized eczema comparison.
Why Tolerability Is The Number We Watch
A treatment that works only helps the patients who keep using it. Phototherapy asks for three sessions a week over three months, which is around 36 appointments, and the usual reason a course fails is that somebody stops going.
That makes the withdrawal column more interesting to us than the EASI column. Two lamps that clear eczema roughly equally are not equivalent in practice if one of them sends patients home with a burn. This is also the strongest argument for treating at home, where the barrier isn’t willingness but the drive to a hospital three times a week.
What This Means For Patients And Physicians
For a dermatologist choosing a lamp for an eczema patient, this trial supports what most units already do. Narrowband is the reasonable default, not so much because it clears eczema better, but because it does the same work with fewer patients dropping out.
For patients, the practical message is that phototherapy is a real option for moderate-to-severe eczema, with about a quarter of patients in each arm of this trial reaching treatment success in 12 weeks. That is a meaningful result for people who would rather not start a systemic drug, and it is worth raising with a dermatologist alongside the newer biologics and JAK inhibitors.
Cytokind’s home units are narrowband, running on Phothera hardware, and they are FDA-cleared and prescribed by a physician who sets the dosing protocol and follows the patient. If you have eczema and want to know whether phototherapy fits your case, talk to us and we’ll help you work through it with your dermatologist.
This article summarizes published research and is not medical advice. Phototherapy is a prescription treatment. Talk with your dermatologist about whether it is appropriate for you.
