Written by the Dermfix phototherapy team · General information, not medical advice.
Short answer: A small but genuine set of randomised controlled trials suggests that low-level light therapy applied to the lower abdomen can reduce the pain of primary dysmenorrhea (period pain without an underlying gynaecological condition), with one trial finding it comparable to a common oral treatment. The evidence base is still modest, so this is best seen as a promising complementary option to discuss with your doctor — not a replacement for medical advice. Here's what the research actually found.
Why light is being studied for period pain
Primary dysmenorrhea is thought to be driven largely by prostaglandins causing uterine muscle contractions and reduced local blood flow. Researchers have explored whether red and near-infrared light — which penetrates into tissue and is associated with effects on local circulation and inflammatory signalling — can ease that pain. The underlying mechanism is the same photobiomodulation pathway we describe in our overview of how red light works.
What the trials found
A skin-adhesive low-level light therapy trial (2016). In a multicentre, randomised, double-blind, placebo-controlled study of women aged 18–35 with primary dysmenorrhea, participants used either a low-level light therapy device or a look-alike placebo, with menstrual pain tracked on a visual analog scale over three cycles. The study reported that the light therapy was safe and effective in improving menstrual pain and quality of life compared with placebo.
A comparison against an oral contraceptive (2022). In a randomised multicentre trial of 156 patients, LED-based low-level light therapy applied to two lower-abdominal points was compared with a standard combined oral contraceptive over three menstrual cycles. Both approaches produced clinically meaningful pain reduction, and the light therapy achieved a similar level of relief to the medication in this study.
Honest framing to keep in the article:
- These are encouraging but early results from a relatively small field.
- Trials used specific devices, placements and doses — outcomes depend on delivering an adequate dose to the right area.
The wavelengths, dose and distance that matter
As with any red-light application, the details decide the result:
- Both red (660 nm) and near-infrared (830–850 nm) are relevant; near-infrared penetrates deeper toward the lower-abdominal tissue involved.
- Dose (J/cm²) = intensity × time, so an honestly measured irradiance matters. A panel that inflates its output using a solar-meter number will leave you under-dosing. We explain why in the Europe buyer's guide.
- An irradiance figure only means something at a stated distance — for home use, roughly 40–100 mW/cm² at 15 cm is a sensible working range.
A compact, targeted panel is usually the practical choice for the lower abdomen — for example the Dermfix RLF750.
How it's typically used
In the studies, treatment was applied over the lower abdomen across several menstrual cycles rather than as a one-off. At home, that translates to short, regular sessions at the stated distance. Use the eye protection supplied and follow the device instructions.
Important: Period pain that is new, severe, worsening, or different from your usual pattern can signal a condition that needs diagnosis (such as endometriosis or fibroids). Red light is not a diagnostic tool or a substitute for medical care — please see a doctor for anything beyond your typical mild-to-moderate period pain.
Frequently asked questions
Can red light therapy help with period pain?
Randomised controlled trials on primary dysmenorrhea have found low-level light therapy applied to the lower abdomen reduced pain versus placebo, and in one trial it was comparable to a combined oral contraceptive. The evidence is promising but the field is still small.
Where is the light applied?
In the studies, over the lower abdomen. Near-infrared wavelengths penetrate deeper toward the tissue involved.
Is it a replacement for my usual treatment?
No — treat it as a complementary option to discuss with your doctor, not a substitute for medical advice or diagnosis.
How many sessions?
The trials ran across three menstrual cycles with regular sessions, so it's a consistent routine rather than a single use.
Sources
- Hong GY, et al. Randomized controlled trial of the efficacy and safety of self-adhesive low-level light therapy in women with primary dysmenorrhea. Int J Gynaecol Obstet. 2016;133(1):37–42. https://pubmed.ncbi.nlm.nih.gov/26797192/
- Comparative evaluation of low-level light therapy and a combined oral contraceptive for clinical efficacy in primary dysmenorrhoea: a prospective randomised multicentre trial. Lasers Med Sci. 2022. https://link.springer.com/article/10.1007/s10103-021-03490-z
- Mechanism background: Hamblin MR. Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation. Photochem Photobiol. 2018. https://pubmed.ncbi.nlm.nih.gov/29164625/
Disclaimer: This article provides general information and is not medical advice. See a qualified professional for period pain that is new, severe, or unusual for you.