Red light therapy
and period pain
Period pain is not something you just have to manage. Red light therapy has a genuine clinical evidence base for menstrual cramps, pelvic pain, and endometriosis symptoms - one that most people have never heard of. Here is what the research actually shows.
The pain that gets dismissed
Around 71% of women globally experience period pain. For up to 20-29% of them, the pain is severe enough to disrupt work, exercise, social plans, and sleep. And yet it remains one of the most under-researched and under-treated conditions in medicine. Many women are told it is normal, offered ibuprofen, or given the pill as a catch-all solution without being properly assessed.
What gets far less attention is that there is a growing body of clinical research into non-pharmacological approaches for menstrual pain - and red light therapy sits near the top of it. A 2025 systematic review pulled together 12 randomised controlled trials covering 645 participants, found statistically significant pain reduction with light therapy compared to sham, and concluded that it represents a safe and effective non-pharmacological option for people who cannot or do not want to use NSAIDs or hormonal treatment. One of those trials compared red light therapy directly against the combined oral contraceptive pill, and the pain relief was comparable.
That is worth repeating. Comparable to the pill. Without the hormones, the mood changes, or the need to take something every day.
Why red light affects period pain
Period pain happens because of prostaglandins - hormone-like compounds released during menstruation that cause the uterus to contract. In women with dysmenorrhea, prostaglandin levels are higher than normal, leading to stronger contractions, reduced blood flow to the uterine muscle, and the hypersensitised pain response that makes cramps so debilitating.
Red light therapy acts on several of these mechanisms at once. The three below are the ones with the most direct clinical evidence.
How red light reduces period pain - three pathways
Prostaglandin reduction
Clinical trials measuring blood markers show that red light therapy reduces serum levels of PGE2 and PGF2α - the prostaglandins that drive uterine cramping. This targets the root cause of primary dysmenorrhea, not just the sensation of pain.
Better blood flow to the pelvis
Red and near-infrared light triggers the release of nitric oxide, which relaxes blood vessels and improves circulation. The uterine ischemia (restricted blood flow) that makes cramps worse is directly addressed by this mechanism.
Reduced inflammation
PBM reduces the inflammatory cytokines that sensitise pain receptors in pelvic tissue. For conditions like endometriosis, where chronic inflammation is a major driver of pain between periods, this matters beyond just the days of bleeding.
Primary dysmenorrhea is menstrual pain without a diagnosable pelvic condition causing it - just the body producing too many prostaglandins during menstruation. It is the most common form of period pain and the one with the most direct clinical trial evidence for red light therapy.
The most comprehensive summary comes from a 2025 systematic review that pooled the results of 12 RCTs. Three trials comparing LLLT to sham treatment showed a statistically significant mean difference in pain scores of -4.02 points on the visual analogue scale (a 0-10 pain rating) at 12 weeks (95% CI -7.21 to -0.82, p=0.01). When compared to oral contraceptives, LLLT showed even greater pain reduction (MD 0.91, 95% CI 0.49-1.33, p<0.0001). No serious adverse events were reported across any of the trials included.
Three numbers that define what the clinical evidence actually looks like.
The two cards below are from the same 2022 multicentre trial - 156 women, 3 consecutive menstrual cycles, comparing red light therapy head-to-head against the combined pill.
of women achieved a clinically meaningful reduction in pain (33% or more decrease on the visual analogue scale). Serum prostaglandin E2 levels fell significantly. No side effects requiring treatment withdrawal.
of women achieved the same threshold. The difference between the two groups was not statistically significant (p=0.084). Both reduced prostaglandin levels. OCP achieved a slightly higher response rate; RLT achieved it without hormones.
A separate 2024 crossover trial (Fu et al., Photonics) tested pulsed 630nm LED light against a white light placebo in 46 women with moderate to severe primary dysmenorrhea. The pulsed red light group showed significant reductions in pain scores compared to placebo. The crossover design - where participants experience both treatments in sequence - is a particularly robust way to assess pain interventions because each person acts as their own control.
What this actually means
If your period pain is driven primarily by high prostaglandin levels - which is the case for most people with primary dysmenorrhea - red light therapy targets that mechanism directly. It is not a painkiller that masks symptoms while the underlying process continues. Several trials measured blood prostaglandin levels before and after treatment, and they fell. That is the biology being addressed, not just the pain signal being blunted.
Endometriosis affects roughly 1 in 10 women of reproductive age in the UK and takes an average of 8 years and 10 months to diagnose - a figure that has been worsening, not improving. The pain - which can include severe cramping, chronic pelvic pain, pain during sex, and pain with bowel movements - comes from endometrial-like tissue growing outside the uterus, driving an ongoing inflammatory response. Standard treatment options include hormonal suppression and surgery, both of which have significant limitations and side effects. Many women are looking for things they can do between or alongside medical treatment to manage day-to-day pain.
The direct RCT evidence for red light therapy in endometriosis is limited but meaningful. Thabet and Alshehri (2018, Photomedicine and Laser Surgery) conducted a randomised controlled trial with 40 women aged 24-32 with mild to moderate endometriosis, comparing pulsed high-intensity laser therapy three times a week for eight weeks against standard care. The treatment group showed a 47% reduction in pain intensity compared to 16% in the control group, along with a significant reduction in adhesions confirmed by ultrasound and improved quality of life scores across physical, psychological, and social domains.
Separately, a clinical cohort study examined transvaginal PBM in 48 women with endometriosis-associated chronic pelvic pain. After 8 treatments: 79.2% improved by at least one point on the pain scale, and 58.3% achieved the minimum clinically important difference - defined as a reduction of two or more points. These are not dramatic numbers, but they are consistent with what PBM does across other chronic pain conditions: meaningful relief for the majority, not a cure for all.
The honest position on endometriosis
Red light therapy is not a treatment for endometriosis. It does not remove endometrial tissue, prevent its growth, or address the underlying hormonal environment driving the condition. What the evidence suggests is that it can reduce the pain and inflammation that endometriosis causes - which for many women is the primary day-to-day burden. It sits alongside medical treatment, not instead of it. If you have endometriosis, any new approach should be discussed with your gynaecologist, particularly if you are on hormonal suppression or preparing for surgery.
The research is compelling, but the obvious question is whether any of it translates to sitting in front of a home panel. For this application, the answer is more direct than most.
The multicentre trials for primary dysmenorrhea used LED devices applied to the lower abdomen - specifically to acupuncture points just below the navel (CV4 and CV6). That is external application, and it is exactly what you would do with a home panel.
Near-infrared wavelengths (810-850nm) penetrate tissue more deeply than visible red light, and the uterus sits approximately 5-8cm below the skin surface depending on body composition. NIR reaches pelvic structures more effectively than red alone, which is why a dual-wavelength panel (red plus NIR) is more relevant for this application than a red-only device.
The practical guidance from the trial protocols points toward consistent, preventive use rather than emergency application during acute pain. Starting sessions 1-2 days before your expected period, when prostaglandin levels are beginning to rise before the bleeding starts, is more effective than waiting until the pain peaks.
The four cards below cover the main ways a panel can be used, in order of how directly they map to clinical evidence.
Preventive use - start before your period
Position the panel over the lower abdomen (below the navel) 1-2 days before your expected period. 10-20 minutes per session. Starting before the pain escalates is more effective than treating it once it has set in - prostaglandins begin rising before bleeding starts.
Lower back as well as abdomen
Many women find lower back pain is as debilitating as abdominal cramping. The same PBM mechanisms - improved blood flow, reduced inflammation, muscle relaxation - apply to the lower back and sacral region. Alternating front and back coverage gives broader pelvic relief.
Between periods for endometriosis
For endometriosis-related pelvic pain, the inflammation driving discomfort does not switch off between periods. Regular sessions (3-5 times a week) throughout the month, targeting the lower abdomen and pelvis, are more relevant than period-focused use alone.
Consistency over intensity
The clinical trials showing the strongest results ran for 3 consecutive menstrual cycles (12+ weeks). Red light therapy is not a single-session fix. The prostaglandin-reducing and anti-inflammatory effects build over repeated sessions - several weeks of consistent use gives a much clearer picture of whether it is working for you than a handful of sessions around one period.
Worth knowing for pelvic use
For period pain and pelvic health specifically, the NovaThera Flex 105 wearable belt is worth considering alongside a panel. It wraps directly around the lower abdomen and lower back, keeping red and NIR light in contact with the target area hands-free - which matters when you want to use it daily in the days before and during your period without having to hold anything in place.
A note on safety
No serious adverse events were reported across any of the clinical trials in this area. The same general red light therapy safety principles apply: avoid use if you are taking photosensitising medications, and discuss with your doctor before starting if you have an active pelvic infection, are pregnant, or have recently had pelvic surgery. Red light therapy should not be used as a reason to delay or avoid medical assessment of pelvic pain - if you have not been properly evaluated for endometriosis, fibroids, or other conditions, that evaluation matters and should come first.
Where this sits in the broader picture
Period pain has a poor track record of being taken seriously. Most women are handed ibuprofen and told to manage. The pill is often prescribed without discussion of alternatives. And conditions like endometriosis go undiagnosed for years while women are told their pain is normal.
None of that changes what the research shows. Twelve randomised controlled trials covering 645 participants. Pain relief comparable to the combined pill in head-to-head comparison. Measurable reductions in the prostaglandins driving the cramps. No serious side effects. That is a meaningful evidence base for a non-pharmacological approach - one that most people with period pain have never been told about.
Red light therapy will not work equally well for everyone. It is not a substitute for medical assessment or treatment. But for the large number of women who are either not tolerating or not getting on with their current pain management options, it is worth knowing the evidence exists and that it is more robust than most. You did not imagine the pain, and you do not have to just get on with it.
Sources
NovaThera
Red and NIR. The wavelengths that matter.
For pelvic applications, near-infrared penetration matters as much as red. NovaThera panels deliver both at verified irradiance levels - with published data to back it up.