Red Light Therapy for Period Cramps: What the Trials Show
Red light therapy for period cramps has support from a small set of trials: red LED light placed on the lower belly eased period pain more than a sham light or a placebo in several studies. Below: what the trials found, how light compares with heat and the pill, trial settings, timing in your cycle, who should not use it, and panel setup at home.
Key takeaways
- In a crossover trial of 40 women, pulsed 630 nm red light lowered average period pain from 6.63 to 3.63 out of 10, while a white-light sham moved it from 7.30 to 6.75. Fu, 2024
- In a large Chinese multicentre trial, 73.6% of women using 630 nm light patches had at least a one-third drop in pain, against 85.7% on the contraceptive pill, a difference that was not statistically significant. Zhu, 2022
- The most common trial routine was 610 to 630 nm light on two points of the lower belly, 20 minutes a day for about 5 days per cycle, over three cycles. Pelevin, 2026
- A heat patch on the lower belly lowered period pain by 40.4 points on a 100-point scale over two days, close to the 39.0 points seen with ibuprofen. Akin, 2001
- The NHS advises seeing a GP if periods become more painful, heavier or irregular, or if the pain stops daily activities. NHS
Does red light therapy for period cramps work?
Small randomised trials suggest it can ease ordinary period pain, with red light on the lower belly beating a sham light or a placebo. The research is promising and still early: the trials are small and come mostly from a few research groups in Korea and China.
All of them studied primary dysmenorrhoea: period pain with no underlying disease.
| Study | Women | Light | Compared with | Main result |
|---|---|---|---|---|
| Shin, 2012 | 31 | Skin-adhesive light patches | Placebo patch | Authors reported an 83% pain reduction rate; placebo gave slight, temporary relief |
| Chinese multicentre trial (Zhu, 2022) | 156 | 630 nm LED patches | Contraceptive pill | Similar share improved; bigger average drop with the pill |
| Same trial (Gu, 2022) | 137 analysed | LED patches | Placebo pill | Pain fell more with light, from the first cycle |
| Same trial (Wang, 2024) | 114 analysed | LED patches | Pill and placebo | Light and the pill both beat placebo |
| Fu, 2024 | 40 | Pulsed 630 nm LED | White-light sham | Pain 6.63 to 3.63, against 7.30 to 6.75 with sham |
A 2012 trial gave 31 women light patches or placebo patches for 20 minutes a day on the 5 days before their period. In the light group, 16 of 21 reported success in the first cycle. Shin, 2012
The same Korean group then ran an 88-woman sham-controlled trial, where the sham device looked identical but its light was blocked. Hong, 2016
In the 2024 crossover trial, the white-light sham looked the same and used the same power. With red light, pain fell by 45.32%, and 55% of women had more than half their pain relieved. Fu, 2024
The Chinese trial was reported in several papers, so count it as one study. Against a placebo pill, pain fell significantly more with light, and the effect showed from the first cycle. No adverse reactions were seen in the light group. Gu, 2022
How might red light ease menstrual cramps?
The leading idea is that light lowers prostaglandins, the chemicals that make the womb contract during a period. Three trials of light therapy for menstrual cramps reported lower prostaglandin levels after a course of light.
Mayo Clinic links higher prostaglandin levels with more severe cramps. Mayo Clinic
- Prostaglandins: PGE2 and PGF2α fell more with light than with a placebo pill. Gu, 2022
- Compared with the pill: PGE2 fell by about 110 pg/mL with light, 106 with the pill and 71 with placebo. Wang, 2024
- A different route from painkillers: a 2026 review suggests light acts upstream of the COX enzyme, which anti-inflammatory painkillers block. Pelevin, 2026
A blood-flow route through nitric oxide is still a hypothesis. Our article on red light therapy for pain and inflammation explains how light acts on cells more generally.
How long and how often did the trials use red light?
Most trials used 20 minutes a day for 5 to 7 days per cycle, repeated for three cycles. The light came from small patches on the skin at low output, centred on two points below the navel.
| Study | Wavelength | Output or dose | Placement | Minutes | Days per cycle | Cycles |
|---|---|---|---|---|---|---|
| Shin, 2012 | Not in the abstract | Not in the abstract | Acupuncture points, on the skin | 20 | 5 days before the period | 1, followed for 6 months |
| Zhu, 2022 | 630 nm, continuous | 1.0 to 2.5 mW/cm², 3.0 J/cm² | Two points on the lower belly midline | 20 | 5 days of every 7, paused during the period | 3 |
| Fu, 2024 | 630 nm, pulsed | About 10 mW/cm² average | About 2 and 4 inches below the navel | 20 | 7 days, before and during the period | 1 per phase |
| Kim, 2026 (protocol) | 610 nm, continuous | 1.8 mW/cm² | Lower belly or lower leg | 20 | 7 days before the period | 3 |
| Review summary | 610 to 630 nm | 3 to 12 J/cm² | Lower belly midline | 20 | 5 days, before or during the period | 3 |
The 2026 review proposes 3 J/cm² as a reference dose. Pelevin, 2026 A new trial design keeps the same pattern. Kim, 2026
The trials enrolled East Asian women. Patches sit on the skin, while a panel lights a broad area from a distance, so the pattern carries over more than the exact numbers.
When in your cycle should you use red light, and can you use it during your period?
Start a few days before your period is due, and repeat the routine for three cycles before you judge it. Using light during the period also appears in the research, and nothing in the trials suggests it is harmful.
The schedules differ:
- 5 days before the expected period: the 2012 Korean trial. Shin, 2012
- 7 days, before and during the period: the 2024 crossover trial. Fu, 2024
- 5 days on, 2 days off, between periods: the Chinese multicentre trial, which paused during bleeding. Zhu, 2022
The light needs bare skin. Underwear can stay on if the belly from navel to bikini line is uncovered. Our article on whether red light therapy works through clothes explains why fabric matters.
Where should the light go: lower belly or lower back?
The trials treated the lower belly, below the navel, so that is the main area. Treating the lower back as well is a comfort choice for people whose cramps spread there.
Mayo Clinic notes that period pain can spread to the lower back and thighs. Mayo Clinic
- Lower belly: the trials used two midline points, about 2 and 4 inches below the navel. A panel covers both at once.
- Lower back: a second session, back to the panel. Our guide to red light therapy for back pain covers lower-back positioning.
Is red light better than a heating pad for period pain?
Heat has the larger evidence base and is the cheap, well-tested first step. Red light is a different option that small trials support, and the two seem to work by different routes.
The NHS suggests a heat pad or a hot-water bottle wrapped in a tea towel on the tummy. NHS
- Heat against ibuprofen: in a 2001 trial, pain fell by 40.4 points with heat alone, 39.0 with ibuprofen, 43.8 with both and 21.9 with neither, on a 100-point scale. Akin, 2001
- Heat across many trials: a 2026 review pooled 57 trials with 5,359 women. At 3 months or more, heat lowered pain by 1.10 cm on a 10 cm scale more than anti-inflammatory painkillers, with fewer side effects. The authors rated the certainty as low. Yuan, 2026
The light trials used outputs too low to warm the skin much. Fu, 2024 Avoid putting a heat pad and a panel on the same skin in the same session. Repeated heat on one patch of skin can cause a mottled rash called erythema ab igne, with heat pads and hot-water bottles a named cause. DermNet
How does red light compare with ibuprofen or the pill?
In the Chinese multicentre trial, a similar share of women improved with light and with the pill, but the pill gave a bigger average drop in pain. The pill also worked faster, while light caught up by the third cycle.
- At least a one-third drop in pain: 73.6% with light and 85.7% with the pill, not a significant difference. Zhu, 2022
- Average drop in pain: 39.3% with light and 59.5% with the pill.
- Speed: the pill helped in the first cycle. By the end of cycle 3, and two cycles later, there was no meaningful difference between them. Wang, 2024
- Side effects: 3 women had a short-lived rash or itching with light, and 9 had reduced appetite on the pill. Zhu, 2022
Standard care starts with anti-inflammatory painkillers, heat and exercise, with hormonal contraception as another option. Mayo Clinic Light fits as an add-on to that care.
Ibuprofen, naproxen and the contraceptive pill are on an official list of medicines that can make skin more sensitive to sunlight. Sun and your medicine Our precautions rule out use with photosensitising medication, so if you take any medicine, check with your pharmacist or doctor before using the panel. See our red light therapy safety guide.
Is pulsed or continuous red light better for cramps?
Both have been used, and continuous light is the simple choice. One human trial used pulsed 630 nm light, while the others used continuous patches.
The pulsed trial did not state its pulse frequency. Fu, 2024 In mice, pulsed red light reduced pain behaviour and prostaglandins more than continuous light at the same average power. IASP, 2024 That is an animal finding, not evidence in people.
If you do use pulse mode, avoid 3 to 30 flashes per second, the range linked to light-triggered seizures. See pulsed vs continuous red light therapy.
Can you use red light if you are trying to get pregnant or breastfeeding?
No. The panel manual says do not use it if you are pregnant, breastfeeding or preparing for pregnancy.
Pregnant women have not been included in red light trials, so there is no safety data for that time. Put the panel away while trying to conceive, through pregnancy and while breastfeeding, and ask your doctor or midwife about pain relief in that time.
When is period pain a reason to see a doctor first?
See a GP when periods change, become more painful or heavier, or when pain stops your normal day. These can be signs of an underlying condition such as endometriosis, which the light trials did not study.
Severe pain can come from endometriosis, adenomyosis, fibroids or pelvic inflammatory disease. NHS
- See a GP: periods become more painful, heavier or irregular, or the pain stops daily activities. NHS
- Urgent GP appointment or NHS 111: pain that is severe or worse than usual, when painkillers have not helped.
- Possible endometriosis: pain with sex, urination or bowel movements, or difficulty getting pregnant. NHS
- Later or worsening cramps: severe cramps that start after age 25, or cramps that get worse over time. Mayo Clinic
- Long or heavy: pain lasting more than 3 days, or coming with heavy bleeding. Cleveland Clinic
Teenagers with painful periods should see a GP too, especially if pain keeps them off school. Our devices are for adults.
How do you use a Kivorla panel for period cramps?
Face the panel with your lower belly bare, about 12 inches away, goggles on, with the red channels on. Start at 5 minutes, use it daily in the few days before your period, and judge it after three cycles.
The 9-Spectrum Red Light Therapy Panel carries 480, 590, 630, 660, 670, 810, 830, 850 and 1060 nm, each dimmable from 1 to 100%. Its 630 nm channel matches the main trials, with 660 and 670 nm close by. Our article on 630 nm vs 660 nm red light compares them.
- Position: hang it on a door or wall with the included door hook, pulley, hanging cables and screws, so the centre sits at lower-belly height. You can also stand it upright on the floor and sit facing it.
- Distance: about 12 inches, our suggested distance for a broad area, on bare skin from the navel to the bikini line.
- Channels: turn on 630, 660 and 670 nm, and set 480 and 590 nm to their lowest setting. Near-infrared is optional and goes beyond what the LED period trials used.
- Timer and mode: continuous light, starting at 5 minutes and building towards 10 minutes per area. If no time is set, the panel stops at 5 minutes.
- Lower back: turn round for a second session if your cramps spread there.
- When: daily for the few days before your period is due, and on days 1 and 2 if you like. Leave at least 6 hours between 30-minute sessions.
- Tracking: score your pain from 0 to 10 on the first two days of each period for three cycles, and note any painkillers you take.
The trials used gentle doses from small patches. To stay near that studied range, keep the distance at 12 inches, dim the red channels below 100% at first, and keep sessions short. The surface stays at or below 40°C: warm is fine, hot is not. Stay awake during sessions, and keep any treatment your doctor prescribed.
The panel is not for use if you have had sunburn on your body in the past 2 weeks, have seizures triggered by light, take photosensitising drugs, have an open wound on the area, or have Fitzpatrick skin type V or VI. Goggles and a controller are included.
Standard shipping to the US, UK and Germany is free. Read the precautions before ordering. Under our return and refund policy, returns are accepted within 30 days: an unopened device with its seals intact is refunded less a 10% restocking fee, and an opened device that is undamaged and complete is refunded less 20%.
Kivorla devices are general wellness devices, not medical devices, and are not intended to treat period pain, dysmenorrhoea or endometriosis. See a GP or gynaecologist for severe, worsening or new period pain, and do not stop prescribed treatment.