Minimal Erythema Dose (MED) Testing

Abstract

Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual's skin sensitivity. Thus, to establish the proper dosage of UV light to administer to a patient, the patient is sometimes screened to determine a minimal erythema dose (MED), which is the amount of UV radiation that will produce minimal erythema (sunburn or redness caused by engorgement of capillaries) of an individual's skin within a few hours following exposure. This article describes how to conduct minimal erythema dose (MED) testing. There is currently no easy way to determine an appropriate UV dose for clinical or research purposes without conducting formal MED testing, requiring observation hours after testing, or informal trial and error testing with the risks of under-or over-dosing. However, some alternative methods are discussed. Video LinkThe video component of this article can be found at

Oral Vitamin D Rapidly Attenuates Inflammation from Sunburn: An Interventional Study

“…1b). The MED to experimentally induce sunburn was determined for each participant during the initial screening visit as previously described (Heckman et al, 2013). Participants were irradiated with one, two, and three times the MED on the sun-shielded, upper arm using plastic holed templates to ensure that adjacent skin was not exposed.…”

A guide to prescribing home phototherapy for patients with psoriasis: The appropriate patient, the type of unit, the treatment regimen, and the potential obstacles

“…These areas are examined 24 to 48 hours later to determine the MED, the minimal duration of exposure that produced erythema. 20 Phototherapy can be started at 0.5 to 0.7 of MED and then increased 5% to 20% with each treatment to maintain a mild erythema throughout treatment, while avoiding severe sunburn-like reactions. [21][22][23][24] Because of the difficulty of determining MED, this method for determining a treatment schedule is not always used, especially with home phototherapy.…”

An open‐label clinical trial assessing the efficacy and safety of Bend Skincare Anti‐Aging Formula on minimal erythema dose in skin

“…In addition, a control group of individuals receiving placebo or no intervention and graders being blinded to the intervention when reading MEDs would have made the results of this study more convincing. A randomized, double‐blind, placebo‐controlled trial, including a nonsubjective assessment of skin redness using a devise such as a spectrophotometer rather than visual inspection, might be appropriate to confirm the beneficial results achieved in this trial. It should also include quantification of pro‐ vs anti‐inflammatory cytokines to pinpoint the mechanisms underlying the apparent anti‐inflammatory effects indicated by changes in MED, as well as markers for UV‐induced DHA damage such as cyclobutane pyrimidine dimers or oxidative DNA damage such as 8oxo‐guanine, to determine the extent of UV protection against DNA damage, if any.…”

“…6,7 In experimental models, sunburn sensitivity is measured using the minimal erythema dose (MED), defined as the smallest UV dose producing perceptible skin redness within distinct borders in a given period of time after exposure. [8][9][10] The higher the MED, the more resistant the skin is to sunburn. Therefore, increased MED following an experimental treatment signifies photoprotection.…”