See Important Safety Information below.
Your alarm goes off, your eyes open, and somehow, after a full eight hours of sleep, it feels like the night never happened. By 10 a.m., the second coffee is gone, and the third is calling. Sound familiar? If the people around you keep saying "you're just stressed" or "try going to bed earlier," but deep down something feels genuinely wrong — trust that instinct.
Constant fatigue isn't just laziness or a lack of motivation. It's often your body waving a red flag, signaling that something physiological deserves attention. And yet, women are routinely told to drink more water, try yoga, or simply rest while real, diagnosable conditions go uninvestigated. Let's dig into what might actually be behind that bone-deep exhaustion.
What causes fatigue in women
Women face a unique set of fatigue triggers that men simply don't deal with. Hormonal fluctuations across menstrual cycles, pregnancy, postpartum recovery, and perimenopause all place enormous metabolic demands on the body. Layer on societal pressures (the mental load of managing households, careers, caregiving, and emotional labor), and it's a recipe for running on empty.
But here's the critical part: there's a difference between feeling tired because life is demanding and feeling an unshakable exhaustion that sleep doesn't fix. The latter often has medical roots. And unfortunately, women's health concerns have historically been minimized or dismissed in clinical settings, meaning these causes go undiagnosed for months or even years.
It's also worth noting that fatigue rarely has a single cause. Multiple factors frequently overlap and compound each other. So, as we walk through these causes, keep in mind that more than one might apply.
Low iron and fatigue
Can iron deficiency cause severe fatigue? Absolutely, and it's one of the most common yet frequently overlooked culprits in women. According to Centers for Disease Control and Prevention (CDC) data from August 2021 through August 2023¹, anemia prevalence was significantly higher in females (13.0%) than in males (5.5%).
Here's the simple science: iron is essential for making hemoglobin, the protein in red blood cells that carries oxygen throughout the body. Less iron means less hemoglobin, which means less oxygen reaching your cells. The result? Your body is essentially running on fumes, and everything from climbing stairs to concentrating at work feels harder than it should.
What many women don't realize is that you can be iron-deficient without being technically anemic. Your ferritin (stored iron) levels can be tanking while your hemoglobin still looks "normal" on a standard blood panel. This is why a full iron panel — including ferritin, total iron-binding capacity (TIBC), and transferrin saturation — matters so much.
Women are particularly vulnerable due to monthly menstrual blood loss, increased demands during pregnancy, and dietary restrictions. Heavy periods and iron deficiency often create a vicious cycle where each condition worsens the other. Beyond fatigue, watch for shortness of breath, dizziness, cold hands and feet, pale skin, and brittle nails.
Oral iron supplements are a common first-line treatment, but they don't work for everyone. Gastrointestinal (GI) side effects, poor absorption, and certain gut conditions can make oral supplementation ineffective. When oral iron fails, isn't tolerated, or isn't appropriate, IV iron infusion is an option, and it's more accessible than many women realize. IV iron bypasses the GI system entirely, delivers iron directly into the bloodstream, and typically works faster than oral supplementation.
Monoferric (ferric derisomaltose) is FDA-approved to replace up to 1000 mg of iron in a single, rapid infusion. Monoferric is used for treating iron deficiency anemia (IDA) when you have previously tried oral iron medications and they have not worked. Monoferric is an intravenous iron treatment, meaning it is administered through your vein from a drip. Monoferric is also used for treating IDA if you have chronic kidney disease but are not dependent on hemodialysis. The dose may be repeated if IDA reoccurs. The intravenous infusion may take 20 minutes or more. Like all IV iron treatments, Monoferric has risks your doctor will discuss with you. Monoferric is contraindicated in patients with a history of serious hypersensitivity to ferric derisomaltose or any of its components, including reactions such as anaphylaxis, shock, hypotension, loss of consciousness, or collapse. Infusions are administered in a monitored clinical setting for this reason. See full prescribing information and Important Safety Information at the end of this article.
The key takeaway: iron deficiency is a common and often overlooked cause of fatigue in women, and appropriate testing is essential before choosing a treatment approach.
Persistent fatigue in perimenopause
If you're in your late 30s or 40s and the fatigue hits you like a wall, perimenopause fatigue² might be the explanation nobody's offering you. This transition can begin years before periods actually stop, and the fatigue it causes is real and debilitating — not just "getting older."
During perimenopause, estrogen and progesterone levels fluctuate wildly rather than declining in a neat, predictable line. These hormonal swings disrupt sleep architecture, trigger night sweats that wake you multiple times, and affect the brain's regulation of energy and mood. Metabolic changes during this phase can also shift how the body processes and stores energy.
This is often compounded by the life stage itself: many women in perimenopause are juggling career peaks, raising kids, and caring for aging parents simultaneously. When exhaustion hits from all directions, it's easy for a provider to chalk it up to lifestyle.
But perimenopause fatigue is treatable. Hormone therapy, sleep interventions, targeted exercise, and nutritional adjustments can make a meaningful difference. The first step is recognizing that this isn't something to just push through.
Thyroid disorders
The thyroid is a small butterfly-shaped gland in the neck that essentially controls the body's metabolic speed. When it's underactive (hypothyroidism), everything slows down: energy production, digestion, heart rate, and even thought processing. When it's overactive (hyperthyroidism), the body burns through energy at an unsustainable pace, also leading to exhaustion.
Thyroid conditions are strikingly common in women, partly due to the autoimmune connection (Hashimoto's thyroiditis, the leading cause of hypothyroidism, is an autoimmune condition) and partly due to the interplay between thyroid hormones and reproductive hormones.
Alongside fatigue, thyroid problems often bring weight changes, temperature sensitivity, brain fog, hair thinning, dry skin, and mood shifts. If these sound familiar, ask for comprehensive thyroid testing³ — not just thyroid-stimulating hormone (TSH), but also free triiodothyronine (T3), free thyroxine (T4), and thyroid antibodies. A TSH level alone can miss early or subclinical thyroid dysfunction.
Finding the right medication and dosage is often a process that takes patience. But once optimized, many women experience dramatic improvements in energy and overall well-being.
Autoimmune conditions and chronic illness
The fatigue that comes with autoimmune conditions like Hashimoto's, lupus, rheumatoid arthritis4, and multiple sclerosis isn't garden-variety tiredness. It's a heavy, flu-like exhaustion that can make even basic daily tasks feel monumental.
Autoimmune diseases present with a clear gender bias. According to research from Stanford Medicine5, as many as 4 out of 5 people with autoimmune disorders are women. Yet despite this striking prevalence, many women endure a years-long diagnostic odyssey — bouncing between specialists, being told their symptoms are psychosomatic, and feeling gaslit by the very system meant to help them.
If fatigue comes with joint pain, rashes, recurring fevers, digestive issues, or other systemic symptoms, advocating for autoimmune panels—antinuclear antibody (ANA), inflammatory markers like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), and other specific antibody tests—is essential.
PCOS and metabolic issues
Polycystic ovary syndrome (PCOS) affects an estimated 1 in 10 women of reproductive age6, and PCOS-related fatigue7 is one of its most debilitating yet least discussed symptoms. The connection often runs through insulin resistance, a hallmark of many PCOS cases, where cells struggle to efficiently convert blood sugar into energy.
This creates a frustrating rollercoaster: blood sugar spikes and crashes trigger cycles of energy surges and deep crashes. Add in the chronic low-grade inflammation common in PCOS and the hormonal imbalances that extend well beyond irregular periods, and the result is a persistent, heavy fatigue that no amount of caffeine resolves.
PCOS is frequently undiagnosed or misdiagnosed, especially in women who don't fit the "classic" presentation. If fatigue comes alongside irregular cycles, unexplained weight gain, acne, or hair changes, it's worth asking about PCOS specifically.
Vitamin deficiencies beyond iron
Iron gets the most attention, but it's far from the only nutrient deficiency that can tank energy levels:
Vitamin D: Often called the "sunshine vitamin," deficiency is extremely common — especially in northern climates, during winter months, and among those with darker skin tones. Low vitamin D is linked to fatigue, muscle weakness, and mood changes.
Vitamin B12: Essential for nerve function and red blood cell production, B12 deficiency is particularly common in vegans, vegetarians, and anyone with gut absorption issues. Fatigue, tingling in hands and feet, and cognitive fog are hallmark symptoms.
Folate and other B vitamins: These play critical roles in energy metabolism, and deficiencies can contribute to fatigue even when other labs look normal.
Standard multivitamins often don't contain therapeutic doses of these nutrients. Actual blood testing, not guessing, is the only reliable way to know where levels stand and what supplementation is truly needed.
Sleep disorders
Sleeping eight hours and still waking up exhausted is one of the most frustrating experiences, and it often points to a sleep disorder. According to a study published in the journal Sleep and Breathing8, examining U.S. females, one in four women in America is at high risk of having obstructive sleep apnea syndrome (OSAS), a condition still widely stereotyped as something that only affects older, overweight men.
Women with sleep apnea often present differently from men. Instead of loud snoring, they may experience insomnia, morning headaches, mood disturbances, and, you guessed it, crushing daytime fatigue. Restless leg syndrome and circadian rhythm disorders can similarly destroy sleep quality without being immediately obvious.
If sleep feels unrefreshing regardless of duration, a formal sleep study can reveal what's happening during those supposedly restful hours.
Mental health matters, too
Depression and anxiety are both causes and consequences of chronic fatigue, creating a bidirectional cycle that can be difficult to untangle. Fatigue is actually one of the most common symptoms of depression, sometimes appearing even before mood changes become noticeable.
This needs to be said clearly: acknowledging that mental health plays a role in fatigue doesn't make the exhaustion any less real or physical. The brain is an organ, and when it's struggling, the whole body feels it. Integrated treatment approaches that address both the mental and physical components tend to be the most effective.
Naming mental health as a contributing factor isn't the same as saying fatigue is "all in your head." It's saying the whole picture matters.
Is it normal to be tired all the time?
No. Full stop. Chronic, unrelenting exhaustion is not a normal part of being a woman, being busy, or being "of a certain age." There's a meaningful difference between feeling tired after a hard week and experiencing a fatigue so deep that it interferes with daily functioning, relationships, and quality of life.
Women have been culturally conditioned to push through, to carry the load without complaint, to accept exhaustion as the price of doing it all. And historically, medical systems have reinforced this by dismissing women's symptoms at higher rates than men's. It's time to stop accepting "you're just stressed" as a diagnosis.
When your blood work comes back "normal"
Few things are more deflating than hearing "your labs look fine" when every cell in your body is screaming otherwise. But here's something important: standard blood panels are designed to screen for disease, not to identify optimal function. The ranges are broad, and falling within them doesn't necessarily mean things are working well for you.
Tests doctors should run, but often don't, include:
Full iron panel (ferritin, TIBC, transferrin saturation), not just hemoglobin
Vitamin D (25-hydroxy)
B12 and folate
Complete thyroid panel (TSH, free T3, free T4, TPO and TG antibodies)
Cortisol
Inflammatory markers (CRP, ESR)
Fasting insulin and glucose
If a provider isn't willing to investigate further, seek a second opinion.
How to actually get answers
Getting to the root of extreme fatigue often requires persistence and self-advocacy. Here are concrete steps:
Track symptoms: Keep a fatigue diary noting when exhaustion is worst, what makes it better or worse, and any accompanying symptoms. Patterns can be powerful diagnostic clues.
Prepare for appointments: Come with written notes, specific examples, and timelines. Use the word "extreme" — language matters in how seriously concerns are taken.
Advocate boldly: If dismissed, try phrases like: "I need you to document that you're declining to test for this" or "What else could this be?" These can shift the dynamic in an appointment.
Bring backup: A partner, friend, or family member at appointments can provide additional observations and support.
Find the right provider: Not every doctor is the right fit. Seek providers who listen, take women's symptoms seriously, and are willing to dig deeper.
Remember: nobody knows your body better than you do. If something feels wrong, it deserves investigation, regardless of what initial tests show.
You deserve to feel like yourself again
Extreme fatigue isn't a character flaw, a consequence of not trying hard enough, or something to just live with. It's your body communicating that something needs attention, and that message is valid.
Whether the answer turns out to be low iron levels9, a thyroid condition, perimenopause, an autoimmune process, or a combination of factors, answers exist. Finding them might take persistence, multiple appointments, and a willingness to push back against dismissal. But with proper diagnosis and treatment, energy can be restored. The version of yourself that doesn't run on caffeine and willpower alone? She's still in there, waiting for the right support to come back.
What is Monoferric?
Monoferric (ferric derisomaltose) is a prescription iron treatment given through a vein (IV) to treat iron deficiency anemia in adults who:
cannot tolerate oral iron or who have not responded well to treatment with oral iron
have non-dialysis dependent chronic kidney disease
IMPORTANT SAFETY INFORMATION
Who should not receive Monoferric?
Do not receive Monoferric if you have had serious allergic reactions to ferric derisomaltose or any of its ingredients.
What are the possible side effects of Monoferric?
Monoferric may cause serious side effects, including:
Allergic (hypersensitivity) reactions. Serious life-threatening allergic reactions have happened in people who receive Monoferric. Symptoms of an allergic reaction including rash, itching, hives, dizziness, lightheadedness, breathing problems, and low blood pressure have also happened during treatment with Monoferric. Tell your healthcare provider right away if you develop any of the above symptoms of a serious allergic reaction or if you have ever had any unusual or allergic reaction to any IV iron in the past.
Too much iron stored in your body (iron overload). Your healthcare provider should check the iron level in your blood before you start and during treatment with Monoferric.
The most common side effects of Monoferric include rash and nausea.
These are not all the possible side effects of Monoferric. Call your doctor for medical advice about side effects.
What should I tell my doctor or healthcare provider before receiving Monoferric?
Before receiving Monoferric, tell your healthcare provider about all your medical conditions, including if you:
have had an allergic reaction to IV iron.
are pregnant or plan to become pregnant. It is not known if Monoferric will harm your unborn baby. Untreated iron deficiency anemia during pregnancy may increase risks for you and your baby.
are breastfeeding or plan to breastfeed. Data from women treated with Monoferric show that iron is present in breast milk. It is not known how Monoferric may affect your breastfed baby.
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.
You are encouraged to report negative side effects to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.
Please see full Prescribing Information including information for patients.
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