What is the lowest dose of progesterone for HRT?

When people begin to experience menopause-related symptoms — whether it’s that first scorching hot flash or the exasperating 2 a.m. wake-ups robbing them of precious sleep — they often want to learn what options they have to get relief. For many, that quest will lead them to considering hormone replacement therapy (HRT), also sometimes referred to as menopause hormone therapy (MHT).

HRT beefs up your body’s declining supplies of estrogen and progesterone brought on by menopause and decreases how much those hormones fluctuate, helping alleviate symptoms like hot flashes, night sweats, sleep disruptions, and vaginal dryness. Although HRT is clinically appropriate for many women, studies have shown a slight increase in risk for certain conditions. As a result, clinicians recommend using the lowest effective dose in order to get the benefits while minimizing risk.

Your doctor will help you determine which dosage is the right prescription for you, but here’s what to know about the lowest dose of progesterone for HRT.

What is progesterone used for in HRT?

Reading about progesterone can get confusing because the terms progesterone and progestin are often used interchangeably. In short: Progesterone is the hormone that occurs naturally in our bodies (you’ll sometimes see what’s called bioidentical progesterone, which is made in a lab and is structurally identical to natural progesterone). Progestin is a synthetic compound that mimics natural progesterone. They’re both common, effective tools in the HRT toolbox, and your doctor will help determine which makes sense for you. For the purposes of this article, the term progesterone is used for both, except when a distinction is needed between the naturally occurring and the synthetic progestin.

Progesterone is usually prescribed in conjunction with estrogen. Think of estrogen as the hero of HRT, and progesterone its trusty sidekick. While estrogen is what helps alleviate many of the symptoms brought on by menopause, taking it by itself can cause the lining of the uterus to thicken and increase the risk of developing uterine cancer. This is where progesterone comes in. Adding it to HRT prevents this thickening of the uterine lining.

On top of that, progesterone can also help counter certain menopause symptoms. “ First and foremost, it helps improve sleep,” said Dr. William Lee, M.D., a certified menopause practitioner and associate professor of clinical obstetrics and gynecology at Vanderbilt Health in Franklin, Tennessee. “It also helps with brain fog, anxiety, and what’s called emotional lability, or the fluctuation of emotions that comes with perimenopause.”

Lowest dose of progesterone for HRT

The right dose of progesterone for you will vary depending on your individual needs and background, as well as factors like estrogen dosage, where you are in your menopausal transition, and which form of HRT you’re using. Your doctor might not need to prescribe progesterone at all if you have an intrauterine device (IUD) that provides a sufficient dose of progestin or if you’ve had your uterus removed. After you begin HRT, keep track of how you’re feeling and work with your doctor to determine whether you need to adjust your progesterone dosage over time.

Oral progesterone

A common form of progesterone for HRT is a capsule you take by mouth. This form of progesterone is well-studied and is usually tolerated well by most people. For the most part, oral progesterone comes in two doses. “100 mg of oral progesterone is the lowest dose that protects the endometrium in menopause from estrogen’s long-term adverse effects,” said Lee. There is a higher dose of 200 mg available as well, but you’d work up to that amount if necessary. “Most doctors will start with 100 mg unless there are bleeding irregularities that we’re trying to control, or unless the patient is really having difficulty sleeping,” said Dr. Melanie Marin, M.D., a certified menopause practitioner and director of the menopause program in the department of obstetrics, gynecology, and reproductive science at the Mount Sinai Health System in New York City.

However, a doctor can prescribe lower than 100 mg if you aren’t taking estrogen. Progesterone levels begin to decline before estrogen levels do, according to Lee. Because of this, he sometimes prescribes progesterone in doses as low as 50 mg to patients who have symptoms of very early perimenopause, such as sleeplessness and mood changes, but who don’t yet need to start taking estrogen to address the full array of menopausal symptoms. One thing to keep in mind: Oral progesterone isn’t prescribed to women with peanut allergies because it contains peanut oil as an ingredient.

Progestin patch

Progesterone is not absorbed through the skin, but the synthetic version, progestin, can be combined with estrogen in a transdermal patch. The Combipatch can contain as low as 0.14 mg of norethindrone (a kind of progestin), while Climara Pro provides 0.015 mg per day of levonorgestrel (a different progestin). The hormones are delivered directly into your bloodstream through your skin, allowing for smaller dosages than oral HRT. “A combination patch is a great option for people who don’t want to take pills, or if oral progesterone makes them too sleepy,” said Marin.

Vaginal progesterone

For some people who can’t tolerate oral progesterone (for example, if it’s causing gastrointestinal issues), a provider could prescribe 100 mg or 200 mg progesterone capsules that can be inserted vaginally. This might have some other benefits as well: One study showed that women who took progesterone vaginally had more regular menstrual bleeding than those taking it orally.

How does progesterone HRT work?

Progesterone is a naturally occurring reproductive hormone that helps prepare the uterus for pregnancy in the reproductive years. It also influences many other bodily functions, such as regulating menstrual bleeding and improving mood. This and the similar drop in estrogen is why things start to go haywire during menopause. As your body’s natural levels of progesterone decline, replacing it as part of HRT can help get some of those functions back on track.

How long do you need to take progesterone HRT?

The length of time you need to take progesterone will depend on how long you take estrogen. Remember: Progesterone’s primary function is to protect against estrogen raising your risk of uterine cancer. And when you stop estrogen depends on many factors. “There’s no arbitrary age or number of years when someone should stop hormone therapy,” said Lee. “Stopping hormone therapy should be a shared decision-making process between the patient and clinician.”

Some women will be on HRT for only a few years, and some will be on it for the rest of their lives. The only way to know whether you no longer need to take HRT is to stop taking it and see how your body responds. If you think you’re ready to stop taking HRT, talk to your doctor about coming up with a plan and a timeline that makes sense for you.

What are the side effects of progesterone HRT?

Most people tolerate progesterone well and don’t experience any problematic side effects. However, if any side effects are seriously affecting your life, your doctor might recommend that you decrease your dosage, switch to a progestin, or take progesterone in another way (like switching from oral to a patch).

Common side effects of progesterone HRT

One side effect of progesterone is often considered a welcome benefit: drowsiness. Since progesterone is known to make you tired, it can actually be beneficial for people having trouble sleeping through the night, a common symptom of menopause. Because of this side effect, your doctor will probably recommend you take your prescribed daily dose in the evening before you go to bed. Here are some other common progesterone side effects:

• Breast swelling and/or tenderness
• Dizziness
• Gastrointestinal issues, such as an upset stomach, diarrhea, or vomiting
• Low mood, increased anxiety
• Bloating
• Joint, bone, and/or muscle pain

Severe side effects of progesterone for HRT

Since people don’t often take progesterone without estrogen, many of the more serious side effects, like a slightly increased risk for blood clots, thrombosis, stroke, or heart attack, are linked to the combination estrogen/progesterone HRT.

There was also a Women's Health Initiative study from 2002 that linked combination HRT with an increased risk of breast cancer. However, Lee points out that the increased risk was linked to a specific synthetic progestin called medroxyprogesterone acetate, not progesterone. It’s important to discuss your family history and personal history with your doctor to decide if HRT is a good fit.

Progesterone does have the potential for some other serious side effects, including:

• Excessive grogginess or dizziness
• Severe mood changes, especially for people with premenstrual dysphoric disorder
• Changes in heart rate or breathing
• Vision changes

The bottom line

Progesterone plays a key role in HRT for menopause, helping protect the uterus from adverse effects of estrogen. Most people tolerate progesterone without significant side effects, but it’s important to work with your doctor so you can find the lowest effective dose of progesterone that works for you. For oral and vaginal progesterone, 100 mg is the lowest common dosage, while transdermal patches can have much lower doses because they use a synthetic form of progesterone and the hormone is delivered directly into the bloodstream via the skin.