Could Low Testosterone Be Behind Your Low Libido, Fatigue, and Brain Fog?
Most women never consider testosterone when they are trying to explain why they feel off. They blame stress, poor sleep, getting older, or doing too much. Sometimes those are the right answers. But sometimes the answer is a hormone that nobody thought to test.
What you will learn in this post
Women produce testosterone. And it matters.
Testosterone gets labeled a male hormone, but women produce it too, primarily in the ovaries and adrenal glands. It plays a direct role in sexual desire, energy levels, muscle maintenance, mood regulation, and cognitive function. It starts declining gradually in most women beginning in their mid-30s, and by age 40 androgen levels have typically dropped by roughly half, well before menopause begins.
That timeline matters because most women and most providers associate hormone changes with menopause specifically. But low testosterone symptoms can appear years earlier and are frequently attributed to other things including stress, depression, poor sleep, or simply getting older. The hormone is rarely the first thing investigated, which means it is often the last thing found.
Six symptoms that could point to low testosterone
None of these symptoms are unique to low testosterone. They each have other possible causes and a proper evaluation always considers those. But when several of these appear together, especially in a woman in her late 30s through 50s, getting a full hormone panel that includes testosterone is a reasonable and often revealing next step.
Low libido or loss of sexual desire
The most recognized symptom. Testosterone plays a direct role in sexual desire and arousal in women. When it drops, interest in sex often fades gradually rather than suddenly, which makes it easy to explain away as stress or relationship issues. It can also show up as fewer sexual thoughts, difficulty reaching orgasm, or a persistent sense of indifference rather than an active aversion.
Persistent fatigue that does not resolve with rest
Not the tired that comes from a busy week and resolves with a good weekend. This is the fatigue that is there when you wake up, stays through the afternoon, and does not meaningfully respond to getting more sleep or slowing down. Testosterone supports energy production and red blood cell function, and when it is low, sustained energy becomes genuinely harder to maintain.
Brain fog and difficulty concentrating
Testosterone has a role in cognitive function, particularly focus, mental clarity, and memory. Women with low testosterone often describe feeling like they are thinking through fog, struggling to hold onto thoughts, or finding tasks that used to be automatic now requiring deliberate effort. This symptom is frequently attributed to stress or perimenopause without testosterone being measured.
Mood changes, anxiety, or emotional flatness
Low testosterone does not always show up as sadness. It sometimes shows up as a blunted emotional experience, a reduced motivation, or an irritability that feels disproportionate. Because these symptoms overlap almost completely with depression and perimenopause, testosterone rarely gets considered unless a provider is running a comprehensive panel.
Muscle weakness and reduced exercise tolerance
Testosterone plays a direct role in maintaining muscle mass. Women with low levels often notice they are losing strength or struggling to make progress in workouts they used to handle comfortably. Recovery takes longer. Building muscle feels harder. This change is commonly attributed to aging or under-eating without any hormonal investigation.
Changes in body composition
Because testosterone supports muscle maintenance, declining levels can shift body composition even without changes in diet or activity. Women may notice they are losing muscle tone and gaining fat more easily, particularly around the midsection. This is often lumped in with general hormone changes but testosterone is a meaningful contributor worth measuring specifically.
Low testosterone symptoms overlap heavily with depression, thyroid dysfunction, perimenopause, and anemia. The only way to know if testosterone is part of the picture is to test it directly, not assume it away.
Why this gets missed so often
There are a few reasons low testosterone in women stays off the radar. First, routine bloodwork does not typically include it. A standard panel checks thyroid and blood counts. Testosterone is not in that order unless someone specifically requests it, which means providers who are not actively looking for it will not find it.
Second, the symptoms overlap significantly with conditions that are more commonly considered: depression, hypothyroidism, iron deficiency, perimenopause, and general burnout. A woman who comes in reporting fatigue, mood changes, and low libido might leave with an antidepressant, a referral to a therapist, or advice to reduce her stress load without her hormone levels ever being fully evaluated. That is not always wrong, but it misses the full picture when testosterone is also a factor.
Third, there is no FDA-approved testosterone product specifically for women, which means many providers are simply less familiar with how to evaluate or treat it. That knowledge gap affects how seriously the symptom gets investigated in the first place.
The evidence on testosterone therapy for women is stronger than most people realize
In 2019 a coalition of major medical organizations including the Endocrine Society, the North American Menopause Society, and the International Menopause Society released a global consensus statement on testosterone therapy in women. Their conclusion was that testosterone therapy can meaningfully improve sexual desire, arousal, orgasm, and satisfaction in postmenopausal women with hypoactive sexual desire disorder (HSDD), with reduced distress as a result. The consensus statement is also honest about where evidence is currently limited. Testosterone is not recommended as a general treatment for fatigue, mood, or other symptoms in isolation. But for low libido specifically, the research is substantial enough that major medical societies agree it is worth properly evaluating and, when indicated, treating.
What a proper evaluation actually looks like
Getting to the bottom of symptoms like fatigue, low libido, and brain fog requires more than a single blood draw. A thorough workup includes thyroid function, iron studies, a complete blood count, and a full hormone panel that covers estrogen, progesterone, and testosterone. Not because testosterone is always the answer, but because it is often the piece that gets left out.
It also means ruling out other contributors before concluding anything. Relationship stress, certain medications including some birth control pills, depression, pelvic pain, and thyroid dysfunction can all reduce libido and energy independent of testosterone. A responsible evaluation considers those factors rather than jumping straight to hormone therapy as a first step.
Want to find out if your testosterone has been properly tested? At Dela we run a full hormone panel that includes what most standard panels skip.
Hormone Testing at DelaHow we approach this at Dela
When a patient comes in describing low libido, persistent fatigue, or brain fog, we do not assume it is stress or aging and leave it there. We run a comprehensive panel that includes testosterone alongside estrogen, progesterone, cortisol, thyroid markers, and metabolic data. Because these hormones interact with each other, looking at one without the others means you are only seeing part of the picture.
If low testosterone is contributing to your symptoms, we will walk you through what the evidence actually supports for treatment, what realistic outcomes look like, and how any treatment plan would be monitored over time. If the panel points somewhere else entirely, like thyroid function or iron levels, we will follow that lead instead rather than steering toward a conclusion before we have seen your results.
These symptoms are not something you have to accept as an inevitable part of getting older. They are worth investigating properly.
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What are the symptoms of low testosterone in women?
The most recognized symptom is low libido or loss of sexual desire. Other common symptoms include persistent fatigue that does not resolve with rest, brain fog and difficulty concentrating, mood changes including anxiety or emotional flatness, muscle weakness and reduced exercise tolerance, and changes in body composition such as losing muscle tone while gaining fat more easily. These symptoms often appear together and are frequently attributed to stress, perimenopause, or depression without testosterone being tested.
How is low testosterone diagnosed in women?
Low testosterone in women is diagnosed through a blood test that measures total and free testosterone levels. A proper evaluation also includes thyroid function, iron studies, estrogen, progesterone, and cortisol because these hormones interact with each other and low testosterone rarely exists in isolation. Standard blood panels do not typically include testosterone for women, so it needs to be specifically requested or ordered as part of a comprehensive hormone panel.
At what age does testosterone start declining in women?
Testosterone in women begins declining gradually starting in the mid-30s. By age 40 most women have testosterone levels roughly half of what they were in their 20s. This decline happens well before menopause which is why some women in their late 30s and early 40s experience symptoms like low libido and fatigue that are connected to testosterone rather than estrogen changes specifically.
Is testosterone therapy safe for women?
When properly dosed and monitored, testosterone therapy is considered safe for women. A 2019 global consensus statement from the Endocrine Society, the North American Menopause Society, and the International Menopause Society concluded that testosterone therapy can meaningfully improve sexual desire and related symptoms in postmenopausal women with hypoactive sexual desire disorder. Because there is currently no FDA-approved testosterone product specifically for women, any treatment should be individualized, carefully dosed, and monitored over time by a provider familiar with hormone therapy. Potential side effects at higher doses include acne and unwanted hair growth.
Does low testosterone cause weight gain in women?
Low testosterone does not cause weight gain directly but it contributes to changes in body composition that can feel like weight gain. Because testosterone supports muscle mass, declining levels make it harder to maintain muscle. Since muscle tissue burns more calories at rest than fat tissue does, losing muscle over time slows metabolism and makes fat gain easier, even without changes in diet or exercise. This is why addressing testosterone alongside estrogen and progesterone gives a more complete picture of midlife body composition changes.
Written by Kallie Pothier, FNP, MSCP
Kallie is a Family Nurse Practitioner and Menopause Society Certified Practitioner and the founder of Dela Women's Health in Pleasant Grove, Utah. She specializes in perimenopause, menopause, and hormonal health for women across Utah County and statewide via telehealth.
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