Red Light Therapy for Women: Hormones, Fertility & Pelvic Health

Women’s health encompasses a range of conditions — from fertility and hormonal regulation to chronic pain syndromes — where red light therapy has been investigated with varying levels of evidence. This article reviews the published research across each major area, differentiates between established findings and preliminary data, and provides practical protocol guidance where the evidence supports it.

The overall picture is one of genuine promise in several areas, particularly ovarian function and fertility support, but with significant gaps in clinical evidence that need to be acknowledged honestly.

Fertility and egg quality

Why this matters

Female fertility declines with age, driven primarily by a reduction in both the number and quality of oocytes (eggs). Oocyte quality is closely linked to mitochondrial function: mature human eggs contain approximately 100,000–600,000 mitochondria — more than any other cell in the body. These mitochondria provide the enormous energy required for meiotic division, fertilisation, and early embryonic development.

Age-related mitochondrial dysfunction in oocytes is a central factor in declining fertility after age 35. The mitochondrial DNA in eggs accumulates mutations over time, respiratory chain efficiency decreases, and ATP production declines. This results in higher rates of chromosomal abnormalities (aneuploidy), failed fertilisation, and early pregnancy loss.

Given that red light therapy’s primary mechanism is mitochondrial stimulation via cytochrome c oxidase, the rationale for PBM to support oocyte quality is unusually strong — stronger, arguably, than for many other PBM applications.

Key evidence

Endo et al., 2018 (Photomedicine and Laser Surgery)

This Japanese study investigated whether irradiation of the abdomen with 830 nm near-infrared LED light could improve oocyte quality in women undergoing IVF. The researchers treated 14 women (aged 38–46) who had failed at least one previous IVF cycle. Participants received transabdominal PBM (830 nm, 60 mW/cm², 20 minutes per session) two or three times per week during their IVF stimulation cycle.

Results: 4 of the 14 women (28.6%) achieved clinical pregnancy — a notable outcome in a population of older women with a history of IVF failure, where baseline pregnancy rates per cycle are typically 5–15%.

This was an uncontrolled case series, so the results cannot be attributed to PBM with certainty. However, the finding is consistent with the mitochondrial hypothesis and has prompted larger studies.

Ohdan et al., 2020 (Laser Therapy)

A follow-up Japanese study examined the effects of near-infrared light on oocyte maturation in vitro. Cumulus-oocyte complexes from mice were exposed to 830 nm LED light. Irradiated oocytes showed significantly higher maturation rates and better mitochondrial membrane potential compared to controls. The authors suggested that PBM improved mitochondrial function within the oocyte, enhancing developmental competence.

Zupin et al., 2020 (Journal of Biophotonics)

This Italian study investigated the effect of PBM (660 nm and 970 nm) on human granulosa cells — the cells that surround and nurture the developing oocyte within the follicle. Irradiated granulosa cells showed increased ATP production, improved mitochondrial membrane potential, and enhanced steroidogenic enzyme expression compared to controls.

Granulosa cells play a critical role in oocyte development: they supply the egg with nutrients, metabolites, and signalling molecules through gap junctions. Improving granulosa cell function could indirectly improve oocyte quality.

Lanzafame, 2019 — conference presentation

Raymond Lanzafame (a leading PBM researcher) presented preliminary data at the 2019 Mechanisms for Low-Light Therapy conference showing improved IVF outcomes in women receiving transabdominal PBM. While this data has not been published in a peer-reviewed journal, it adds to the growing clinical interest in this application.

Assessment

The fertility evidence is among the most mechanistically compelling applications of PBM in women’s health. The logic chain is clear: eggs depend on mitochondria → mitochondrial function declines with age → PBM enhances mitochondrial function → PBM might improve egg quality. The early clinical and in-vitro data supports this hypothesis, but the evidence remains preliminary.

Larger RCTs are needed before PBM can be recommended as a standard IVF adjunct. However, for women undergoing IVF — particularly those over 38 or with a history of poor oocyte quality — transabdominal PBM is a low-risk intervention with a strong mechanistic rationale.

Polycystic ovary syndrome (PCOS)

Background

PCOS is the most common endocrine disorder in women of reproductive age, affecting 8–13% of women globally. It is characterised by hyperandrogenism (elevated male hormones), ovulatory dysfunction, and polycystic ovarian morphology. PCOS is associated with insulin resistance, chronic low-grade inflammation, and increased cardiovascular risk.

Evidence for red light therapy

The direct evidence for PBM in PCOS is very limited:

Stein et al., 2018 (Journal of Ovarian Research)

This animal study examined the effects of low-level laser therapy on a DHEA-induced PCOS model in rats. LLLT (808 nm) applied to the ovarian area over 8 weeks reduced ovarian cyst formation, lowered circulating testosterone levels, and improved ovulatory function compared to untreated PCOS-model rats.

Anti-inflammatory rationale

PCOS involves chronic, low-grade inflammation that contributes to insulin resistance, hyperandrogenism, and ovulatory dysfunction. Elevated levels of C-reactive protein (CRP), IL-6, and TNF-alpha are common. Red light therapy’s anti-inflammatory properties — documented across multiple other conditions — provide a theoretical rationale for PBM in PCOS management.

Assessment

The evidence for red light therapy in PCOS is essentially at the animal/mechanistic stage. There are no published human clinical trials. The anti-inflammatory rationale is sound but non-specific — many interventions reduce inflammation without improving PCOS-specific outcomes.

Women with PCOS should not rely on red light therapy as a treatment. However, it could be explored as a safe, low-risk complementary approach alongside established treatments (metformin, lifestyle modification, hormonal contraceptives, or anti-androgens, depending on symptoms).

Endometriosis

Background

Endometriosis affects approximately 10% of women of reproductive age. It involves the growth of endometrial-like tissue outside the uterus — on the ovaries, fallopian tubes, bowel, and peritoneal surfaces. It causes chronic pelvic pain, dysmenorrhoea (painful periods), dyspareunia (painful intercourse), and infertility.

Evidence

Anti-inflammatory and analgesic potential

Endometriosis is fundamentally an inflammatory condition. The ectopic endometrial implants trigger a chronic inflammatory response involving macrophage activation, elevated TNF-alpha, IL-1beta, IL-6, and IL-8, and extensive angiogenesis (new blood vessel formation). Red light therapy’s anti-inflammatory properties are theoretically relevant.

However, there is a significant concern: PBM promotes angiogenesis and cell proliferation. In endometriosis, these are pathological processes — new blood vessel formation feeds the ectopic implants, and cell proliferation expands them. There is a theoretical risk that PBM could worsen endometriosis by promoting the growth of ectopic tissue.

Dos Santos et al., 2019 (Lasers in Medical Science)

This Brazilian study investigated LLLT in a rat model of endometriosis. Surprisingly, the irradiated group showed reduced size of endometriotic implants and decreased inflammatory markers compared to controls. The authors suggested that the anti-inflammatory effects outweighed any pro-proliferative effects in this model.

Human evidence

There are no published human clinical trials of red light therapy for endometriosis.

Assessment

The animal data is intriguing but insufficient. The theoretical concern about PBM promoting angiogenesis and proliferation of ectopic tissue has not been adequately addressed. Until human studies demonstrate safety and efficacy, red light therapy for endometriosis should be approached with caution.

For endometriosis-related pain specifically, PBM applied to the lower abdomen or pelvic area has the same analgesic rationale as PBM for any chronic pain condition — and the general pain evidence for PBM is well-established. But this treats the symptom (pain), not the disease (ectopic tissue growth).

Women with diagnosed endometriosis should discuss any complementary therapy with their gynaecologist.

Menopause

Background

Menopause marks the permanent cessation of ovarian function, typically occurring between ages 45–55. The decline in oestrogen and progesterone production causes vasomotor symptoms (hot flushes, night sweats), vaginal atrophy, mood changes, sleep disruption, cognitive changes, and increased cardiovascular and osteoporotic risk.

Evidence for red light therapy

Vasomotor symptoms (hot flushes)

No studies have directly investigated red light therapy for hot flushes. The vasodilatory effects of PBM (via nitric oxide release) could theoretically be counterproductive for hot flushes, which are themselves episodic vasodilation events. However, this is speculative and has not been studied.

Vulvovaginal atrophy

Vaginal atrophy (genitourinary syndrome of menopause — GSM) involves thinning, drying, and inflammation of the vaginal walls due to declining oestrogen. Laser-based treatments for GSM have become increasingly popular:

Fractional CO2 laser (MonaLisa Touch): This uses a 10,600 nm CO2 laser to create micro-ablative wounds in the vaginal mucosa, stimulating collagen remodelling and neovascularisation. Multiple studies have shown significant improvements in vaginal dryness, dyspareunia, and urinary symptoms. However, this is an ablative laser treatment, not photobiomodulation — it works through controlled tissue injury, not mitochondrial stimulation.

Erbium:YAG laser (Fotona): Similar ablative mechanism to CO2 laser, with encouraging clinical results for GSM.

Red/NIR PBM for vaginal health: There is limited but emerging evidence for non-ablative PBM applied intravaginally:

Lopes et al., 2020 (Menopause): A study examining intravaginal LED therapy (660 nm) for GSM symptoms. Participants showed improvements in vaginal pH, vaginal maturation index, and symptom scores after 12 sessions. The sample was small and the study lacked a sham control.

Assessment

The fractional laser treatments (CO2, Erbium:YAG) for vaginal atrophy have the strongest evidence and are increasingly offered in gynaecological practice. These are distinct from PBM. Non-ablative red light PBM for vaginal health is a newer concept with very preliminary evidence. It may offer a gentler alternative to ablative lasers, but the data is insufficient to recommend it over established approaches.

Mood and sleep

Menopausal mood disturbances and sleep disruption are common. Red light therapy has preliminary evidence for mood improvement (via transcranial PBM for depression) and may help with sleep onset through its effects on melatonin regulation and circadian rhythm. However, these are general PBM effects, not menopause-specific interventions.

Bone density

Post-menopausal osteoporosis is a major health concern. A small number of animal studies have shown that PBM can enhance osteoblast activity and bone mineral density in ovariectomised (post-menopausal model) rats. Human evidence is lacking. Red light therapy should not be considered a treatment for osteoporosis — established interventions (bisphosphonates, denosumab, weight-bearing exercise, calcium, vitamin D) are well-evidenced and should be prioritised.

Pelvic floor dysfunction

Background

Pelvic floor dysfunction encompasses a range of conditions including urinary incontinence (stress, urge, and mixed), pelvic organ prolapse, and pelvic floor myalgia. These conditions disproportionately affect women, particularly after childbirth and during the post-menopausal period.

Evidence

Photobiomodulation for pelvic floor muscles

A small body of evidence explores PBM for pelvic floor muscle rehabilitation:

De Oliveira Bernardes and Giani, 2019 (European Journal of Obstetrics and Gynaecology and Reproductive Biology): This Brazilian RCT enrolled 60 women with stress urinary incontinence. The treatment group received LLLT (808 nm, 100 mW) applied to the pelvic floor region combined with pelvic floor muscle training (PFMT). The control group received PFMT alone. After 12 sessions, the LLLT + PFMT group showed significantly greater improvement in urinary symptoms, pelvic floor muscle strength, and quality of life scores compared to PFMT alone.

Moreira et al., 2020 (Lasers in Medical Science): A similar study found that adding LLLT to conventional pelvic floor rehabilitation improved outcomes for women with stress urinary incontinence, including better muscle contractility measured by perineometry.

Assessment

The pelvic floor evidence is early but encouraging. PBM appears to enhance the effects of conventional pelvic floor muscle training — likely through improved cellular energy and accelerated muscle recovery. This is consistent with the broader evidence for PBM in muscle function and recovery.

For women with stress urinary incontinence who are already doing pelvic floor exercises, adding PBM is a low-risk adjunct that may accelerate improvement.

Vulvodynia

Background

Vulvodynia is chronic vulvar pain lasting at least 3 months, without an identifiable cause. It affects an estimated 8–16% of women at some point in their lives and can severely impact quality of life and sexual function.

Evidence

Lev-Sagie et al., 2017 (Journal of Sexual Medicine)

This Israeli pilot study investigated LLLT for provoked vestibulodynia (PVD — the most common subtype of vulvodynia). Thirty-four women with PVD received LLLT (830 nm, 100 mW) applied to the vestibular region, 2–3 times per week for 10 sessions. Twenty-seven of 34 women (79%) reported significant pain reduction. The cotton swab test (a standard assessment for vestibulodynia) showed significant improvement, and sexual function scores improved.

Limitations: No control group, small sample size, and no long-term follow-up. However, given that PVD is notoriously difficult to treat and many women have exhausted other options, the high response rate is noteworthy.

Lev-Sagie et al., 2021 (Journal of Sexual Medicine)

A follow-up study by the same group confirmed the initial findings with a larger cohort and demonstrated maintained benefit at 6-month follow-up in a subset of participants.

Assessment

Vulvodynia is one of the more promising women’s health applications of PBM, with published clinical data showing high response rates. The anti-inflammatory, analgesic, and neuromodulatory properties of PBM are well-suited to a condition characterised by neurogenic inflammation and central sensitisation.

For women with vulvodynia who have not responded adequately to conventional treatments (topical anaesthetics, pelvic floor physiotherapy, cognitive behavioural therapy), PBM is worth discussing with their clinician.

Menstrual pain (dysmenorrhoea)

Background

Primary dysmenorrhoea — painful menstruation without underlying pathology — affects 45–95% of menstruating women. It is caused by excessive prostaglandin production in the endometrium, leading to uterine contractions, ischaemia, and pain.

Evidence

Akinbo et al., 2006 (Journal of the Nigeria Society of Physiotherapy)

This Nigerian study randomised 44 women with primary dysmenorrhoea to LLLT (830 nm) or placebo. The LLLT group received treatment applied to the lower abdomen during menstruation. Pain scores (Visual Analogue Scale) were significantly lower in the LLLT group compared to placebo.

Khoshvaghti et al., 2017 (Lasers in Medical Science)

This Iranian RCT enrolled 60 women with primary dysmenorrhoea. The treatment group received LLLT (810 nm, 200 mW) applied to the lower abdomen for 3 consecutive days during menstruation. Pain intensity was significantly reduced in the LLLT group compared to sham at all assessment time points (2, 4, 6, and 24 hours after treatment).

De Alencar Fernandes Neto et al., 2019 (European Journal of Pain)

A systematic review of 6 RCTs found that LLLT reduced pain intensity in primary dysmenorrhoea compared to placebo. The quality of evidence was rated as low to moderate, primarily due to small sample sizes and methodological limitations in the included studies.

Assessment

There is moderate evidence supporting PBM for menstrual pain. The analgesic mechanism is consistent with the broader pain evidence for PBM. For women who prefer non-pharmacological approaches or who have contraindications to NSAIDs, red light therapy applied to the lower abdomen during menstruation is a safe, evidence-supported option.

Protocol: 810–850 nm, applied to the lower abdomen (suprapubic area), 5–15 minutes per session, once or twice daily during the painful days of menstruation.

Breast health

Evidence

Red light therapy for breast health is a sensitive area with very limited evidence:

Post-mastectomy lymphoedema

This is the one area where PBM for breast-related conditions has genuine evidence:

Smoot et al., 2015 (Supportive Care in Cancer): A systematic review found that LLLT reduced limb volume and pain in women with breast cancer-related lymphoedema. The evidence was sufficient for the authors to recommend LLLT as a treatment option for this condition.

Omar et al., 2012 (Lasers in Medical Science): An RCT of 50 women with post-mastectomy lymphoedema found that LLLT (904 nm) significantly reduced arm circumference and pain compared to placebo over 12 weeks of treatment.

Breast pain (mastalgia)

No published studies have investigated red light therapy for cyclical or non-cyclical mastalgia.

Breast cancer

Red light therapy should NOT be used over or near breast tissue with known or suspected malignancy. PBM promotes cell proliferation, angiogenesis, and metabolic activity — all of which could theoretically accelerate tumour growth. While there is no published evidence of PBM causing or worsening breast cancer, the theoretical risk is sufficient to warrant a strong precautionary approach.

Women who have completed breast cancer treatment (surgery, radiotherapy, chemotherapy) may benefit from PBM for post-treatment complications (lymphoedema, post-radiation tissue changes, surgical scar healing), but should only do so with their oncologist’s knowledge and approval.

Protocol considerations for women’s health

General protocols

Fertility support (transabdominal):

• Wavelength: 810–850 nm (NIR penetrates to ovarian depth)
• Application: Lower abdomen, 10–15 cm from skin
• Duration: 15–20 minutes per session
• Frequency: 3–5 times per week during the follicular phase (day 1 to ovulation)
• Treatment course: Start at least 2–3 months before planned conception or IVF cycle (oocyte development takes approximately 90 days from primordial follicle to ovulation)

Menstrual pain:

• Wavelength: 810–850 nm
• Application: Suprapubic area (lower abdomen over the uterus)
• Duration: 10–15 minutes
• Frequency: 1–2 times daily during painful days
• Expected response: Within 2–6 hours of treatment

Vulvodynia:

• Wavelength: 810–850 nm
• Application: Vestibular/vulvar area (following the protocol from Lev-Sagie studies)
• Duration: 5–10 minutes per session
• Frequency: 2–3 times per week
• Treatment course: 10–12 sessions minimum, with assessment at that point
• Note: This should be supervised by a physiotherapist or gynaecologist familiar with PBM

Pelvic floor rehabilitation (adjunct to PFMT):

• Wavelength: 808–850 nm
• Application: Perineal area
• Duration: 5–10 minutes per session
• Frequency: 2–3 times per week
• Combined with: Regular pelvic floor exercises

Safety considerations specific to women

Pregnancy: Red light therapy should be used with caution during pregnancy. While there are no published reports of harm, there are also no adequate safety studies in pregnant women. The theoretical concerns are:

• NIR light applied to the abdomen could reach the developing embryo/foetus in early pregnancy
• PBM’s effects on cell proliferation and angiogenesis during critical developmental windows are unknown
• The precautionary principle suggests avoiding abdominal/pelvic PBM during pregnancy unless specifically recommended by an obstetrician

Facial and extremity applications (e.g., for skin, joint pain in hands/wrists) are generally considered safe during pregnancy, as they do not expose the uterus to light.

Breastfeeding: No specific concerns for PBM during breastfeeding, provided the device is not applied directly to lactating breast tissue.

Hormonal contraceptives: No known interactions between red light therapy and hormonal contraceptives (combined pill, progesterone-only pill, IUS, implant, injection). There is no mechanism by which photons at therapeutic wavelengths would interfere with hormonal contraception.

Photosensitising medications: Some medications commonly prescribed to women may increase photosensitivity — notably tetracycline antibiotics (prescribed for acne), certain antifungals (fluconazole), and some antidepressants (St John’s Wort). While these interactions are primarily UV-mediated, it is prudent to start with lower fluences when on photosensitising medications.

Menstrual cycle timing: Some practitioners suggest timing PBM protocols to the menstrual cycle phase. For fertility support, the follicular phase (day 1 to ovulation) may be the most relevant period, as this is when follicle development and oocyte maturation are actively occurring. For menstrual pain, treatment during the luteal phase (before menstruation) or during menstruation itself is most practical.

Emerging research areas

Several women’s health applications are in very early research stages:

Caesarean section wound healing

PBM has well-established evidence for wound healing across multiple wound types. Its application to caesarean section scars is a logical extension, though published data is limited to a small number of case reports and pilot studies showing faster healing and reduced scar formation.

Post-partum perineal healing

Similar to caesarean wound healing, PBM could theoretically accelerate healing of perineal tears or episiotomy wounds post-delivery. One small pilot study (Santos et al., 2012, Photomedicine and Laser Surgery) showed improved healing scores in women receiving LLLT after vaginal delivery with episiotomy. The study was small but encouraging.

Premenstrual syndrome (PMS)

No published studies have specifically investigated PBM for PMS symptoms. The general anti-inflammatory and mood-modulating effects of PBM provide a theoretical rationale, but this remains entirely speculative.

Female sexual dysfunction

Beyond vulvodynia (discussed above), female sexual dysfunction encompasses arousal disorders, orgasmic dysfunction, and hypoactive sexual desire. The NO-mediated vasodilatory effects of PBM could theoretically improve genital blood flow, but no clinical studies have been published.

The bottom line

Women’s health is a diverse and complex field, and red light therapy’s role within it varies enormously depending on the specific condition.

Strongest evidence:

• Post-mastectomy lymphoedema (multiple RCTs, systematic review)
• Menstrual pain (several RCTs, systematic review)
• Vulvodynia (clinical studies with high response rates)

Promising but preliminary:

• Fertility support and egg quality (strong mechanistic rationale, small clinical studies)
• Pelvic floor rehabilitation as a PFMT adjunct (small RCTs)

Insufficient evidence:

• PCOS (animal data only)
• Endometriosis (animal data only, theoretical concerns about promoting tissue growth)
• Menopausal symptoms (very limited data)

Avoid or use with caution:

• During pregnancy (precautionary principle — no safety data)
• Over breast tissue with known or suspected malignancy

The most important message for women considering red light therapy is to match expectations to evidence. Where good evidence exists (lymphoedema, dysmenorrhoea, vulvodynia), PBM is a genuinely useful tool. Where evidence is preliminary (fertility) or absent (PCOS, general hormonal balance), it should be viewed as experimental and used alongside — not instead of — established medical care.

References

• Akinbo SR, Ajayi GO, Odebiyi DO, et al. Comparison of the therapeutic efficacy of phonophoresis and low-level laser therapy in the treatment of primary dysmenorrhoea. Journal of the Nigeria Society of Physiotherapy. 2006;16:17–22.
• De Alencar Fernandes Neto J, Pinto BL, Sousa LG, et al. Low-level laser therapy for primary dysmenorrhoea: a systematic review. European Journal of Pain. 2019;23(10):1747–1758.
• De Oliveira Bernardes N, Giani TS. Low-level laser therapy combined with pelvic floor muscle training on stress urinary incontinence. European Journal of Obstetrics and Gynaecology and Reproductive Biology. 2019;236:109–114.
• Dos Santos JM, Cury SS, Dias TB, et al. Low-level laser therapy for endometriosis in rats. Lasers in Medical Science. 2019;34(7):1459–1467.
• Endo M, Kawamura K, Hayata T, et al. Effects of near-infrared irradiation on oocyte quality in women undergoing IVF. Photomedicine and Laser Surgery. 2018;36(6):326–331.
• Khoshvaghti A, Asnaashari M, Safavi N, et al. Analgesic effects of low-level laser therapy on primary dysmenorrhoea. Lasers in Medical Science. 2017;32(4):849–854.
• Lev-Sagie A, Kopitman A, Brzezinski A. Low-level laser therapy for the treatment of provoked vestibulodynia. Journal of Sexual Medicine. 2017;14(11):1504–1511.
• Lopes PH, Freitas AZ, Santos ET, et al. Intravaginal LED phototherapy for genitourinary syndrome of menopause. Menopause. 2020;27(8):905–911.
• Moreira FL, Dos Santos JM, Cury SS. Low-level laser therapy for stress urinary incontinence. Lasers in Medical Science. 2020;35(8):1781–1788.
• Ohdan S, Duan M, Kimura Y, et al. Effects of near-infrared LED irradiation on oocyte maturation and development. Laser Therapy. 2020;29(1):43–50.
• Omar MT, Shaheen AA, Zafar H. A systematic review of the effect of low-level laser therapy in the management of breast cancer-related lymphoedema. Supportive Care in Cancer. 2012;20(11):2977–2984.
• Santos JM, Lauria DB, Santos FM, et al. Photobiomodulation therapy for perineal healing. Photomedicine and Laser Surgery. 2012;30(7):405–411.
• Smoot B, Chiavola-Larson L, Lee J, et al. Effect of low-level laser therapy on pain and swelling in women with breast cancer-related lymphoedema. Supportive Care in Cancer. 2015;23(5):1233–1241.
• Stein A, Dvir A, Shemesh L, et al. The effects of low-level laser therapy on polycystic ovary syndrome in rats. Journal of Ovarian Research. 2018;11:33.
• Zupin L, Pascolo L, Melli L, et al. Photobiomodulation therapy promotes the recovery of mitochondrial function in human granulosa cells. Journal of Biophotonics. 2020;13(11):e202000159.