A drop in sex drive is one of the most common sexual health complaints, and it rarely has a single cause. About 27% of premenopausal women and more than half of postmenopausal women report low sexual desire, and the numbers for men climb steadily after age 40. If your libido has faded, something specific is almost always driving it, whether that’s a hormonal shift, a medication, a health condition, or a stretch of poor sleep and high stress. Here’s what’s most likely going on.
Hormones Play a Bigger Role Than You Think
Testosterone is the primary hormone behind sexual desire in both men and women. In women under 50, levels below about 25 ng/dL suggest a deficiency. In women over 50, the threshold drops to around 20 ng/dL. Men typically notice a decline in desire when testosterone falls below the normal range, which can happen gradually starting in the 30s at a rate of roughly 1% per year.
Estrogen matters too, especially for women approaching or past menopause. Falling estrogen levels reduce blood flow to the genitals, thin vaginal tissue, and can make sex uncomfortable, which in turn dampens interest. Longitudinal data from a major U.S. study found that 24% of postmenopausal women reported they never felt sexual desire, and another 41% said they rarely did.
Thyroid hormones are another hidden factor. An underactive thyroid slows your metabolism and can flatten your interest in sex alongside your energy levels. Even a mildly abnormal thyroid can contribute to the problem, which is why it’s one of the first things a doctor should check.
Your Medication May Be the Culprit
Antidepressants are the most common medication-related cause of lost libido. Among people taking SSRIs (the most widely prescribed class of antidepressants), about 39% develop some form of sexual dysfunction. Decreased desire specifically affects roughly 45% of users. Paroxetine carries the highest risk, with nearly 60% of patients reporting reduced libido in one study. Other SSRIs and SNRIs cause it at lower but still significant rates.
The mechanism is straightforward: these drugs increase serotonin activity, which suppresses dopamine signaling. Dopamine is the neurotransmitter most closely tied to motivation and reward, including sexual motivation. The effect can start within weeks of beginning the medication and sometimes persists even after stopping.
Other medications that commonly suppress sex drive include certain blood pressure drugs (especially older beta-blockers), anti-seizure medications, opioid painkillers, and some antihistamines. If your libido dropped around the time you started a new prescription, that timing is probably not a coincidence.
Birth Control and Sex Drive
Hormonal contraceptives can reduce libido by raising levels of a protein called sex hormone binding globulin, or SHBG. This protein binds to testosterone in the bloodstream, making less of it available to your body. Higher SHBG means less free testosterone, which can directly lower desire.
The data on how many women are affected varies widely. Prospective studies have found that about 5% of women on combined oral contraceptives report decreased libido, but some research puts the figure much higher. One placebo-controlled trial found that half of women on combined pills reported losing sexual interest compared to their baseline. Progestin-only injections seem to have a lower impact, with about 6% of users reporting reduced desire.
If you suspect your birth control is the issue, switching to a non-hormonal method or a different formulation is a reasonable first step to discuss with your prescriber.
Chronic Health Conditions
Diabetes is one of the most damaging conditions for sexual function. Persistently high blood sugar creates a chain reaction: it generates oxidative stress that destroys nitric oxide, the molecule your blood vessels need to dilate and increase blood flow to the genitals. Over time, high blood sugar also stiffens blood vessel walls, damages nerve endings that carry sexual sensation, and promotes chronic low-grade inflammation that accelerates the whole process. About one-third of men with type 2 diabetes develop low testosterone as a secondary effect, driven by obesity, insulin resistance, and that same inflammation.
Cardiovascular disease works through overlapping pathways. Anything that narrows or stiffens your arteries reduces blood flow everywhere, including to the genitals. In fact, erectile dysfunction in men often appears years before a heart attack or stroke, because the smaller penile arteries clog before the larger coronary arteries do.
Metabolic syndrome, the cluster of conditions that includes high blood pressure, high blood sugar, excess belly fat, and abnormal cholesterol, doubles the risk of sexual dysfunction in women. One study found a 38% rate of sexual dysfunction in women with metabolic syndrome compared to 19% in healthy controls.
Sleep, Weight, and Stress
Sleep apnea has a direct, measurable effect on sex hormones. When your airway collapses repeatedly during sleep, the resulting drops in oxygen and constant sleep fragmentation suppress testosterone production at the brain level. Research shows that severe obstructive sleep apnea is associated with significantly lower testosterone and higher rates of erectile dysfunction in men, independent of body weight. The relationship works in both directions: obesity worsens sleep apnea, and sleep apnea worsens the hormonal disruption that obesity already causes.
Chronic stress floods your system with cortisol, which competes with sex hormones for the same raw materials and shifts your body’s priorities away from reproduction. Sleep deprivation from any cause, not just apnea, suppresses testosterone. Even a week of sleeping five hours a night can lower a young man’s testosterone by 10 to 15%.
Excess body fat itself converts testosterone into estrogen through an enzyme in fat tissue, which is one reason why weight loss often improves libido, sometimes dramatically.
Relationship and Psychological Factors
Sexual desire doesn’t live in a vacuum. Unresolved conflict, emotional distance, resentment, or simply the routine of a long-term relationship can all erode desire without any biological cause. Depression is a particularly common driver. The loss of interest in things you used to enjoy is a hallmark of depression, and sex is no exception. This creates a frustrating loop when the antidepressants used to treat it can further suppress libido.
Performance anxiety, body image concerns, and past trauma also play significant roles. These psychological factors can coexist with physical ones, making it hard to tease apart what’s doing what without some investigation.
What Testing Looks Like
If low libido persists for several months and bothers you, a blood workup can help identify or rule out hormonal and metabolic causes. A thorough panel typically includes total testosterone, SHBG (to calculate how much testosterone is actually available), thyroid stimulating hormone, prolactin, estrogen, and markers for blood sugar and metabolic health. Elevated prolactin, for instance, can suppress desire and occasionally signals a small, benign pituitary growth that’s easily treated.
For a formal diagnosis of hypoactive sexual desire disorder, symptoms need to have lasted at least six months and must cause you genuine distress. That distress requirement is important: some people have lower baseline desire and are perfectly content with it. The diagnosis exists for people who notice a change and are bothered by it.
What Can Actually Help
The most effective approach depends entirely on the cause. If a medication is responsible, switching to an alternative (a different antidepressant class, for example) often restores desire. If hormones are low, testosterone replacement in men has strong evidence behind it. Testosterone therapy for women is used off-label in some countries and shows benefit, though it’s less standardized.
For premenopausal women with persistent low desire that isn’t explained by medications or relationship issues, two FDA-approved drugs exist. One is a daily pill that works on brain chemistry related to dopamine and serotonin. The other is a self-administered injection taken before sexual activity. Neither is a blockbuster: in clinical trials, about 25% of women on the injection saw meaningful improvement in desire scores compared to 17% on placebo, and 40% of users experienced nausea. These medications exist as options, but their modest benefit means they work best as part of a broader strategy rather than a standalone fix.
Lifestyle changes carry no side effects and address multiple causes at once. Losing 5 to 10% of body weight improves testosterone, reduces inflammation, and can alleviate sleep apnea. Treating sleep apnea with a CPAP device has been shown to improve both testosterone levels and sexual function. Regular exercise, particularly strength training, boosts testosterone and improves mood. Reducing alcohol, which suppresses arousal and disrupts hormone production, can make a noticeable difference within weeks.
For relationship-driven causes, couples therapy or sex therapy with a trained professional has some of the best outcomes of any intervention, particularly when communication has broken down or desire discrepancy between partners is creating tension.