Can the Mirena IUD cause Menopause-like Symptoms in the Vagina?

Quite a few people asked Dr. Jen!

I have been asked about routinely recommending vaginal estrogen with a Mirena (levonorgestrel) IUD multiple times in the past few weeks. And after some thought, I realized I’d never been asked this before. Why now? Why so many queries all of a sudden?

The Mirena was FDA approved over 20 years ago and I’ve inserted a lot of them. I also see people every day with complex vaginal symptoms, but I don’t think I’ve run into a “Mirena causes menopause-like vaginal symptoms” situation before. If anyone had heard about this, you’d think I would have.

So there are two options. A new study is out, or, somewhere in the bowels of the Internet, someone started a rumor. 

There is no new study.

But First, Genitourinary Syndrome of Menopause (GUSM) - A Short Primer

I’ve written about GUSM a few times, most recently here in relation to oral contraceptives.

To summarize, GUSM occurs when estrogen levels drop. This causes changes in the collagen in the vagina and hence a loss of elasticity (meaning the tissues don’t stretch as well). The lining of the vagina (known as the mucosa) thins and becomes fragile and the vaginal microbiome also changes. The end result is dryness, irritation, a sandpaper like feeling, vaginal discharge, a change in odor, an increased risk of urinary tract infections, and pain and even bleeding with sexual activity. This responds very well to vaginal estrogen.

But the Mirena doesn’t affect estrogen levels, meaning it can’t cause GUSM. But can it cause other changes that might feel like GUSM or be misdiagnosed as low estrogen?

Some Basics about the Mirena 

The Mirena contains levonorgestrel, which is a synthetic hormone with progesterone-like qualities. The IUD works via the impact of levonorgestrel on cervical mucus. While levonorgestrel levels are highest in the first few after insertion and can suppress ovulation during this time for some people, over time as the hormone levels drop. But don’t panic, while estrogen levels are lower in the first few months, they are not in the menopausal range and ovulation is back to baseline by six months or so after insertion. Meaning, for the vast majority of the time there is no effect on estrogen.

In the original clinical trials, about 10% of people developed vaginal infections (these studies followed over five thousand women for up to five years). This does not mean these infections were caused by the IUD, because there was no control group. Remember, people get yeast infections and bacterial vaginosis and some of those people will happen to have also recently had an IUD inserted. Just looking at yeast alone, 5% of women will have at once one vaginal infection a year. Meaning this 10% is easily explained by the baseline rate of vaginal infections. After all, vaginitis is the most common or one of the most common reasons that people seek gynecological care. In studies, discontinuation of the Mirena due to vaginal infections occurs less than 1% of the time, which reinforces the fact that IUD-related infection issues are uncommon. 

Now this isn’t a post about vaginal infections, but vaginitis or vaginal infections could be a proxy for vaginal irritation that might be misdiagnosed as GUSM.

The Impact of the Mirena on the Vagina

If the progestin in the IUD were a source of irritation, and hence cause symptoms that could be misdiagnosed as GUSM, we should see it most commonly in the first few months after insertion when levels are highest and then these issues should improve overtime. In addition, we should see vaginal irritation with other contraceptives that use much higher doses of progestins. For example, the progestin-only birth control pill and the hormone implant Implanon, but neither of these products have been linked with vaginal irritation. So, it’s highly doubtful the IUD with it’s much lower dose would have that effect.

There has been research looking at the impact of the levonorgestrel-IUD on the microbiome. The data shows no association, with one exception. One study does suggest that irregular bleeding with the Mirena may be a risk factor for bacterial vaginosis, meaning for those who have irregular bleeding there could be an impact on the microbiome. If this turns out to be true in future studies, it’s not a hormone effect, but due to the blood. 

So What About the Claims of Needing Vaginal Estrogen with the Mirena?

As the Mirena is good for seven years, if you get it inserted when you are 39 and you are now 45 and developing symptoms of genitourinary syndrome of menopause and need vaginal estrogen, that is not unexpected because now you are 45 years old!

I suspect if this Mirena-vaginal estrogen combo prescribing is really happening it’s because of misinformation (meaning providers or people getting a Mirena erroneously think the Mirena commonly and negatively impacts the vagina in a way that can be treated with estrogen). Another possibility is other causes of pain with sex or vaginal irritation are being misdiagnosed as GUSM, meaning many people may be getting vaginal estrogen when they should be getting something else. 

Sometimes people have symptoms that we can’t explain, so if I had a patient with a Mirena and pain with sex or another bothersome vaginal symptom that I couldn’t otherwise diagnose, I might try vaginal estrogen. Given the safety and the beneficial impact of estrogen on collagen and on the microbiome, it may be worth a try, but the idea that it is common or routine to give vaginal estrogen with a Mirena isn’t supported by any data nor by my long history of caring for people with complex vaginal concerns. 

References

Mirena FDA package insert https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/021225s040lbl.pdf

Mirena NDA https://www.fda.gov/media/152355/download

Benedict K, et.  al. Survey of incidence, lifetime prevalence, and treatment of self-reported vulvovaginal candidiasis, United States, 2020;Benedict et al. BMC Women’s Health (2022) 22:147.

Krog MC, et. al. The healthy female microbiome across body sites: effect of hormonal contraceptives and the menstrual cycle. Hum Reprod. 2022 Jul; 37(7): 1525–1543.

Bastianelli C, et. al. The effect of different contraceptive methods on the vaginal microbiome, Expert Review of Clinical Pharmacology. 2021:14:7, 821-836.

Achilles SL, et. Impact of contraceptive initiation on vaginal microbiota Sharon L. Achilles, M Am Journal of Obst Gynecol 2018;622.e10.

Erol O, et. al. The impact of copper-containing and levonorgestrel-releasing intrauterine contraceptives on cervicovaginal cytology and microbiological flora: a prospective study. Eur J Contracept Reprod Health Care. 2014 Jun;19(3):187-93.