A placebo-controlled study showed that 800 mg to 1,200 mg per day of magnesium oxide did not have a significant effect in reducing hot flash symptoms in menopausal women with a history of breast cancer. A smaller study did show a positive effect with 400 mg to 800 mg per day, but did not include a placebo (control) group. Further research is needed in a more generalized population.

Magnesium has been shown to have many health benefits, including effects on blood sugar levels, muscle and bone health, nerve support, and help with trouble sleeping (insomnia) and blood pressure control. It has also been associated with migraine prevention.

The safest way to get magnesium may be through your diet, as your kidneys can help adjust to safe levels. First, check with your healthcare provider if you think you may want to take a magnesium supplement long-term to be sure your kidneys are healthy.

Side effects with magnesium supplements in general may include mild diarrhea, stomach cramping, nausea and headache.

Studies of magnesium for hot flashes

Overview

1. A well-controlled, placebo-controlled study showed that 800 mg per day or 1,200 mg per day of magnesium oxide did not have a significant effect in reducing hot flash symptoms in menopausal women with a history of breast cancer.
2. A small, non-randomized pilot study did show that oral magnesium oxide supplements at lower doses may help reduce severity of weekly hot flashes by up to 50% and weekly frequency of hot flashes by 41% in menopausal breast cancer patients. Due to the non-randomized study design with a placebo and the small study population, further research is suggested.

1. Randomized, placebo-controlled study

A double-blind, placebo-controlled, randomized trial evaluated 289 postmenopausal women with a history of breast cancer, hot flashes and wanting treatment. Participants reported bothersome hot flashes of greater than 28 times per week. Approximately 84% of women were also taking concurrent anti-estrogen therapy (tamoxifen or aromatase inhibitor).

Patients received either 800 mg (n=97) or 1,200 mg (n=96) daily of magnesium oxide or a corresponding placebo (n=96). A placebo is a medicine that has no active medicine and was used to help determine how effective magnesium was for menopausal symptoms in the group that received it.

To evaluate the effectiveness of magnesium compared to placebo, researchers looked at the patient differences between the hot flash score, comparing results from the start of the study (baseline) to the end of treatment.

Hot flash frequency and hot flash score (calculated by multiplying the number of hot flashes by mean severity) were measured using a standardized hot flash diary. Self-reported surveys and phone interviews were used to gather data on frequency, severity and any possible side effects.

Results

• While hot flash score and frequencies decreased over the 8 week period, no statistically significant differences were found between the two active magnesium groups (800 mg and 1,200 mg per day) and the placebo groups with respect to mean hot flash scores and mean hot flash frequencies (see Table 1 and Table 2).
• P-values were reported as 0.67 for the magnesium 1,200 mg vs placebo group, and 0.13 for the magnesium 800 mg vs. placebo group for Mean Hot Flash Scores and 0.55 for the magnesium 1,200 mg vs placebo group, and 0.25 for the magnesium 800 mg vs. placebo group for Mean Hot Flash Frequencies.
• No difference was found in serum magnesium levels between any study arms. No correlation was found between magnesium levels and changes in hot flash symptoms.
• Diarrhea was reported more frequently in the magnesium groups compared to the placebo group, while constipation was more frequent in the placebo group.

Table 1. Mean Hot Flash Scores

	Placebo	Mg oxide 800 mg/day	Mg oxide 1,200 mg/day
Baseline	17.3	16.2	15.6
Week 1	15.5	14.3	14.5
Week 4	12	11.7	10.1
Week 8	11.4	12.1	9

Table 2. Mean Hot Flash Frequencies

	Placebo	Mg oxide 800 mg/day	Mg oxide 1,200 mg/day
Baseline	8.9	8.5	7.6
Week 1	8	7.8	7.2
Week 4	6.7	6.4	5.3
Week 8	6.4	6.6	4.9

^{Table data from Park, et al.}

2. Pilot study

In a Phase 2 pilot study, magnesium oxide 400 mg, escalating to 800 mg if needed, was given at bedtime for 4 weeks to 25 women (average age 53.5 years). The women, who had at least 14 hot flashes per week, were being treated for breast cancer. A pilot study is small research study typically conducted before a larger study to help address study design and research process.

The women were receiving other medications including tamoxifen, aromatase inhibitors or antidepressants, which can lead to hot flashes as a side effect.

Weekly hot flash frequency and weekly hot flash score (frequency x severity), calculated at the beginning of the study was compared to the end of treatment.

Results

• Hot flash frequency per week was reduced by 41% (52 to 28, p=0.02). Hot flash score was also significantly reduced from 110 to 48, a 50.4% reduction (p=0.04). Overall, 56% of patients (14) had at least a 50% reduction in hot flash score.
• Other menopausal symptoms like fatigue, abnormal sweating and distress due to hot flashes were significantly reduced. Many women continued treatment after the study was stopped. Seventeen women escalated the study dose during the study.
• Reported side effects included mild diarrhea in 2 women, while headache and nausea occurred in one woman each, which led to study discontinuation. Magnesium oxide is well-known to cause diarrhea as a side effect, and lower doses at the start of treatment may help to minimize this effect.

Related questions

• When is the best time to take magnesium, morning or night?
• Should I take magnesium with or without food?
• Does magnesium help with bloating and digestion?

What is menopause and its related symptoms?

Menopause is a natural transition when women go from having normal menstrual periods to no periods at all. You are considered to be in menopause when you have not had a period for a full year after the age of 40. Menopause usually occurs between ages 47 to 53.

During menopause, the ovaries stop making eggs and produce less estrogen and progesterone, which are sex hormones. After menopause, you can no longer become pregnant.

Menopausal hormone changes can lead to mood changes, fatigue, hot flashes, insomnia, vagina dryness, pain during sex, and changes in sexual and urinary function. Perimenopause is a phase that may start about 4 years before menopause and cause symptoms similar to menopause.

Read More: Magnesium Guide: Benefits, Types, Food & Dosage

Alternatives to magnesium for menopausal symptoms

Treatment is not a requirement for menopausal symptoms, but many women do seek therapy to improve hot flashes, sleep, sexual intercourse and overall quality of life. Several treatment options are approved by the FDA to address symptoms.

• Guidelines from the American College of Obstetricians and Gynecologists (ACOG) emphasize the use of oral or transdermal hormonal therapy (HT) as the most effective treatment for vasomotor symptoms (hot flashes and night sweats), in patients who can safely use them (without medical issues like breast cancer or other cancers, heart or liver disease, blood clots or undiagnosed vaginal bleeding).
• In addition, low-dose vaginal estrogen can be used in women with vaginal dryness, vaginal irritation, and pain during or after intercourse (sex). These comes as creams, rings, tablets and suppositories.
• Non-hormonal options are also available for hot flashes and include certain antidepressants like Brisdelle (paroxetine).
• Lifestyle changes such as exercise, diet changes and stress reduction can also have added benefits.

The following list of medications are FDA approvals for treatment of menopause and related menopausal symptoms. Some products may be available as a more affordable generic option; ask your pharmacist.

• Bijuva (estradiol and progesterone)
• Brisdelle (paroxetine)
• Duavee (bazedoxifene and conjugated estrogens)
• Estrace (vaginal cream)
• Estring (estradiol vaginal ring)
• Imvexxy (estradiol vaginal insert)
• Intrarosa (prasterone)
• Osphena (ospemifene)
• Premarin (conjugated estrogens vaginal cream)
• Vagifem (estradiol vaginal tablet)
• Veozah (fezolinetant)
• Yuvafem (estradiol vaginal tablet)

To learn more about costs, coupons and generic options for these products, visit the Drugs.com Pricing Guide.

The American College of Obstetricians and Gynecologists (ACOG) recommend the use of FDA-approved bio-identical products rather than custom compounded products due to limited information about safety and efficacy.

Related: Does Bijuva contain bio-identical hormones and what are they?

Contact your healthcare provider to discuss FDA approved options to help relieve menopausal symptoms like hot flashes, night sweats, vaginal dryness or pain from sex. Also, talk to your doctor to determine if it is better for you to use hormonal or non-hormonal menopausal treatments based on your specific medical history.

Bottom Line

• A well-controlled, placebo-controlled study showed that 800 mg/day or 1,200 mg/day of magnesium oxide did not have a significant effect in reducing hot flash symptoms in menopausal women with a history of breast cancer. A smaller study did show a positive effect with lower dosages, but did not include a placebo (control) group.
• Further studies are needed to determine overall effectiveness of magnesium for menopausal symptoms, particularly in the general population.
• Alternative options, proven in clinical studies and available with a prescription from your healthcare provider, can help to alleviate symptoms like hot flashes, vaginal dryness, mood changes and pain during or after sex. Contact your healthcare provider for further information.

This is not all the information you need to know about menopause and menopausal treatment and does not take the place of your doctor’s directions. Discuss any medical questions you have with your doctor or other health care provider.

Read this next: Magnesium 101: Benefits, types, foods & dosage guide

References

• Park H, Qin R, Smith TJ, et al. North Central Cancer Treatment Group N10C2 (Alliance): a double-blind placebo-controlled study of magnesium supplements to reduce menopausal hot flashes. Menopause. 2015 Jun;22(6):627-32. doi: 10.1097/GME.0000000000000374
• Park H, Parker GL, Boardman CH, et al. A pilot phase II trial of magnesium supplements to reduce menopausal hot flashes in breast cancer patients. Support Care Cancer. 2011 Jun;19(6):859-63. doi: 10.1007/s00520-011-1099-7
• Kaunitz AM, Manson JE. Management of Menopausal Symptoms. Obstetrics and Gynecology. 2015;126(4):859-876. doi:10.1097/AOG.0000000000001058.

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