Am I in Perimenopause? Symptoms at 40, Testing, and When Hormone Therapy Makes Sense

Key Takeaways: 

• Perimenopause can start in your 40s, or even your late 30s. It ends after 12 months in a row without a period.
• Hot flashes, poor sleep, brain fog, joint aches, and irregular cycles are all common early signs.
• Hormone blood tests usually aren't reliable for diagnosing perimenopause, because hormone levels swing from day to day.
• Hormone therapy guidance changed in 2025–2026. The FDA announced it would remove most boxed warnings from menopausal hormone therapy labels.
• FDA-approved bioidentical hormones exist and work well for many women. Compounding can help when an approved product doesn't fit your needs.

What is perimenopause? 

Perimenopause is the transition leading up to menopause. During this time your estrogen levels begin to fall, and they rise and dip unpredictably along the way. Cleveland Clinic notes it usually starts in your mid-40s, about eight to 10 years before menopause. It lasts about four years on average and can last up to eight.

Menopause itself is one moment in time. It's the point when you've gone 12 months in a row without a period. According to the National Institute on Aging, the average age of menopause in the U.S. is 52.

You're far from alone. About 2 million U.S. women enter perimenopause every year, according to The Menopause Society.

Can perimenopause start at 40?

Yes. Most women notice perimenopause in their 40s. Mayo Clinic notes that some notice changes as early as their 30s, and others not until their 50s.

It's also common to be unsure whether it's happening. A 2026 survey of more than 7,600 U.S. women found that 34% weren't sure which reproductive stage they were in. Among women ages 40 to 44, that number rose to 42% (The Menopause Society).

Starting early may also mean symptoms last longer. In the long-running SWAN study, women whose hot flashes began while their periods were still regular had them for a median of 11.8 years (SWAN).

What are the first signs of perimenopause?

Symptoms vary a lot from woman to woman. These are some of the most common:

The good news is that the brain fog appears to be temporary for most women. SWAN researchers found that the ability to improve with practice returned in early postmenopause (SWAN fact sheet).

Important: You can still get pregnant during perimenopause. If you don't want to become pregnant, keep using contraception until your provider says otherwise (The Menopause Society).

Is there a test for perimenopause?

Usually not a reliable one. Mayo Clinic says there's no single test or symptom that shows you've started perimenopause. Testing your hormone levels may help you and your health care provider understand how your hormone levels are changing if you're experiencing symptoms.

If you're under 40: see a healthcare professional if you've missed three or more periods. Early changes can signal primary ovarian insufficiency or another condition that needs attention (The Menopause Society).

When does hormone therapy make sense?

Bioidentical hormone replacement therapy (BHRT) is the most effective treatment for hot flashes and night sweats. Here's what current guidance says.

For most healthy women, the benefits outweigh the risks when BHRT starts early. The Menopause Society's 2022 position statement says the benefits of hormone therapy outweigh the risks for most healthy women with symptoms who are under 60, or within 10 years of menopause onset (The Menopause Society).

The FDA updated its warnings. On November 10, 2025, the FDA announced it would work with manufacturers to remove references to heart disease, breast cancer, and probable dementia from the boxed warning on menopausal hormone therapy. It kept the boxed warning about endometrial cancer for systemic estrogen-only products (FDA). The first six products received updated labels on February 12, 2026 (FDA).

Options during perimenopause include:

• Low-dose hormonal birth control (pill, patch, or ring). It's often used in perimenopause to steady cycles and ease symptoms (The Menopause Society).
• Estrogen therapy. If you still have a uterus, you'll also need progesterone to protect the uterine lining. Micronized progesterone is bioidentical, meaning it's structurally identical to the hormone your body makes, and it's available in FDA-approved form. (The Menopause Society).
• Vaginal estrogen for dryness and urinary symptoms. It can be used at any age and for long periods.
• Non-hormonal prescriptions such as fezolinetant, elinzanetant, certain SSRIs, or gabapentin, for women who can't or prefer not to use hormones (Mayo Clinic).

Many women still aren't getting care. In a 2025 Mayo Clinic study of nearly 5,000 women ages 45 to 60, more than 80% of women with menopause symptoms had not sought medical care (Mayo Clinic News Network). That's changing. Hormone therapy use among women ages 45 to 54 nearly tripled between 2017 and 2026 (Epic Research).

Where do compounded hormones fit?​

There are many FDA-approved bioidentical options, such as estradiol and progesterone. If you have trouble accessing commercially available bioidentical options or require a custom solution, contact your local compounding pharmacy.

Compounding makes sense when an approved product doesn't fit your needs. The American College of Obstetricians and Gynecologists (ACOG) notes compounding can be appropriate when an exact product isn't commercially available, or when a patient needs different ingredients or a different form because of an allergy or other need (ACOG Clinical Consensus No. 6). For example:

• An allergy to an inactive ingredient. ACOG's own example is a peanut allergy, since a common FDA-approved progesterone capsule contains peanut oil.
• Sensitivity to dyes, fillers, or adhesives in commercial products.
• A strength that isn't made commercially, or a dose your provider wants to adjust gradually.
• A different form, such as a cream, for someone who can't swallow capsules.

When should I call my doctor?

Don't wait for your next annual visit if you notice any of these (Mayo Clinic):

• Very heavy bleeding, or bleeding that lasts longer than seven days
• Bleeding between periods, or periods that come less than 21 days apart
• Any bleeding after you've gone 12 months without a period
• Symptoms that disrupt your sleep, work, relationships, or quality of life

How can I prepare for my appointment?

Coming in with notes makes it much easier for your provider to spot patterns. For two to three months, track:

1. The start and end dates of each period, and how heavy the flow is
2. Hot flashes or night sweats: how often and how intense
3. Sleep quality, and how often you wake at night
4. Mood, focus, and memory changes
5. New aches, headaches, or migraines
6. All medications and supplements you take, and any known allergies or sensitivities

Frequently asked questions

How long does perimenopause last?

About four years on average, but it can last eight years or more. It ends once you've gone 12 months in a row without a period.

What's the youngest age perimenopause can start?

Most women start in their 40s, but some notice changes in their late 30s. If you're under 40 and have missed three or more periods, see a healthcare professional to rule out other causes.

Can a blood test tell me if I'm in perimenopause?​

Not reliably. Hormone levels swing from day to day during perimenopause, so one test is only a snapshot. Some patients prefer at-home saliva testing kits to track their hormone levels as they age. Your provider may still order labs, such as a thyroid test, to rule out other conditions.

Does perimenopause cause weight gain?​

Weight changes are one of the symptoms The Menopause Society lists for the menopause transition. Sleep loss, muscle changes, and shifting hormones can all play a part. Ask your provider about strength training and nutrition during this stage.

Is hormone therapy safe in your 40s?​

For most healthy women with bothersome symptoms who are under 60, or within 10 years of menopause, the benefits generally outweigh the risks. Your provider will look at your personal and family history to decide what's right for you.

Are compounded bioidentical hormones better than FDA-approved hormones?​

No. They aren't inherently better or safer. FDA-approved bioidentical options work well for many women. Compounding is valuable when you are unable to find your commercially available prescription or when you need a strength, form, or ingredient list that commercial products don't offer.

Talk with a pharmacist who takes the time​

At The Compounding Lab, we've served families in the Dayton area for more than 75 years. We work alongside your provider to make sure your hormone therapy fits you, whether that means a commercially available product or a custom preparation.

Questions about your prescription? Call us at (937) 723-2885 or visit us at 7415 Old Troy Pike, Huber Heights, OH.

About the author

Robyn Crow, RPh, is a pharmacist at The Compounding Lab in Huber Heights, Ohio. Robyn and the rest of our compounding pharmacy team works closely with patients and prescribers to create customized medications for women's health, pain management, pediatrics, and more.

This article is for educational purposes only. It isn't a substitute for professional medical advice, diagnosis, or treatment. Always talk with your healthcare provider about your symptoms and treatment options.

Sources

• The Menopause Society: 2022 Hormone Therapy Position Statement
• The Menopause Society: Perimenopause
• The Menopause Society: Menopause Symptoms
• The Menopause Society: Hormone Therapy
• The Menopause Society: Many Women Still Confused About Perimenopause (2026)
• The Menopause Society: Premature Menopause
• Cleveland Clinic: Perimenopause
• Cleveland Clinic: Do At-Home Menopause Tests Work?
• Mayo Clinic: Perimenopause Symptoms and Causes
• Mayo Clinic: Perimenopause Diagnosis and Treatment
• Mayo Clinic News Network: Most Midlife Women With Menopause Symptoms Do Not Seek Care (2025)
• National Institute on Aging: What Is Menopause?
• SWAN Study: Symptoms Across the Menopause Transition (PMC)
• SWAN Study: Up to 14 Years of Hot Flashes
• Climacteric (2024): The Musculoskeletal Syndrome of Menopause
• FDA: HHS Removes Misleading Warnings on Hormone Replacement Therapy (Nov. 2025)
• FDA: Labeling Changes Approved for Menopausal Hormone Therapy Products (Feb. 2026)
• ACOG Clinical Consensus No. 6: Compounded Bioidentical Menopausal Hormone Therapy
• Epic Research: Hormone Therapy Use Nearly Doubled Since 2017 (2026)