The most dismissed entry on this list, and often the most fixable. When sex stops happening because there is nothing left by the time there is an opportunity, that is a symptom with causes, not a motivation problem or a verdict on the relationship.
How common: Extremely common and rarely raised as a sexual health issue at all, which is why the treatable causes behind it go unchecked for years.
See someone about this if
Fatigue with unexplained weight loss, night sweats that are not menopausal, breathlessness, or new lumps needs assessment promptly.
Fatigue with low mood, hopelessness, or loss of interest in everything is depression and deserves treating in its own right.
Falling asleep during the day, or at the wheel, needs urgent medical attention.
Narrow it down
This page narrows the question; it does not answer it. Everything below is written so that you can walk into an appointment with a date, a pattern, and a specific thing to ask — which is the difference between a consultation that goes somewhere and one that does not.
Is the tiredness there all day, not only in the evening?
All-day fatigue points at something testable — thyroid, iron, sleep apnoea, hormones — rather than at scheduling.
17 classes of commonly prescribed medicine are associated with fatigue or sedation getting in the way. Associated does not mean responsible in your case, and it never means stop taking anything — this is a list of things worth raising with whoever prescribed them.
Antipsychotic medicinesCommonly reportedProlactin rise is the usual mechanism, and it varies a lot by drug.
BenzodiazepinesCommonly reportedSedation and blunting rather than a direct genital effect.
Beta-blockersCommonly reportedLong blamed; the evidence is weaker than the reputation.
Cytotoxic chemotherapyCommonly reportedCan trigger early menopause and affects tissue directly.
GnRH analoguesCommonly reportedShuts down sex hormone production; effects are profound and expected.
MirtazapineCommonly reportedLower orgasm impact than SSRIs; sedation is the bigger obstacle.
Opioid pain medicinesCommonly reportedLong-term use suppresses sex hormone production.
Sedating antihistaminesCommonly reportedDry mucous membranes everywhere, including vaginal tissue.
Tricyclic antidepressantsCommonly reportedSerotonin effects plus a drying, sedating anticholinergic action.
19 conditions on this site list fatigue or sedation getting in the way among their effects. A condition appearing here is not a suggestion that you have it — it is a list of things a clinician can rule in or out, several of which are a single blood test away.
Breast cancer treatmentCommonly reportedEndocrine therapy causes severe dryness for years, and it is treatable.
DepressionCommonly reportedThe condition and its treatment pull in the same direction, which makes attribution hard.
EndometriosisCommonly reportedDeep pain with penetration, and an average diagnostic delay measured in years.
Heart diseaseCommonly reportedFear of the effort is usually a bigger obstacle than the effort.
Inflammatory arthritisCommonly reportedPain, stiffness, fatigue, and a body-image burden that goes unmentioned.
Inflammatory bowel diseaseCommonly reportedUrgency, fatigue, perianal disease, and body image after surgery.
Low testosteroneCommonly reportedTestable, treatable, and frequently caused by something else on this site.
Multiple sclerosisCommonly reportedDirect nerve effects, plus fatigue, plus the medicines — all three at once.
Obstructive sleep apnoeaCommonly reportedMassively under-diagnosed, and it suppresses testosterone directly.
Parkinson's diseaseCommonly reportedMovement, autonomic, and dopamine effects — in both directions.
Postpartum recoveryCommonly reportedHormones, healing tissue, and exhaustion arriving at once.
Prostate cancer treatmentCommonly reportedErection, ejaculation, and desire all change — and rehabilitation exists.
Sjögren's syndromeCommonly reportedDries every mucous membrane — and the vaginal one is rarely asked about.
Thyroid conditionsCommonly reportedOne of the most testable and most missed causes of low desire and fatigue.
Uterine fibroidsCommonly reportedDeep pain and heavy bleeding, both of which reshape a sex life.
The list is short, the tests are cheap, and the yield is high.
Thyroid problems, iron deficiency and anaemia, and vitamin D deficiency.
Low testosterone, including opioid-related suppression.
Diabetes, and sleep apnoea — which is enormously under-diagnosed and produces exactly this pattern.
Sedating medicines
Sedation is a listed effect of a large share of commonly prescribed medicines.
Sedating antihistamines, including the ones sold over the counter as sleep aids.
Mirtazapine, benzodiazepines and z-drugs, gabapentinoids, and beta-blockers.
Opioid pain medicines, which add hormonal suppression on top of the sedation.
Sleep and load
The obvious causes, which are obvious because they are usually right.
Genuine sleep debt, shift work, and small children.
Caring responsibilities and an uneven share of domestic work, which is a sexual health factor whether or not it gets counted as one.
Menopausal night sweats fragmenting sleep without anyone identifying it as the reason.
Mood
Fatigue is a core symptom of depression, not a side issue.
Depression, which flattens energy and desire together.
Burnout, which looks similar and responds to different things.
What helps in the meantime
Ask for a blood test before assuming this is life rather than physiology — thyroid, iron, and glucose cover most of the treatable ground.
Move intimacy out of the last hour of the day; for many couples that single change does more than anything else on this page.
Treat the domestic load as part of the problem, because for a lot of people it is most of it.
Take these to an appointment
Could we check thyroid function, iron, and glucose?
Should I be assessed for sleep apnoea?
Are any of my medicines contributing to the sedation?
Matters more if: menopause-related dryness.
Common questions
What causes too tired for sex?
The most dismissed entry on this list, and often the most fixable. When sex stops happening because there is nothing left by the time there is an opportunity, that is a symptom with causes, not a motivation problem or a verdict on the relationship. The causes worth ruling out fall into a few groups: testable medical causes, sedating medicines, sleep and load, mood, and medicines. Most people turn out to have more than one contributing at once.
How common is too tired for sex?
Extremely common and rarely raised as a sexual health issue at all, which is why the treatable causes behind it go unchecked for years.
Can medication cause too tired for sex?
Yes — 17 classes of commonly prescribed medicine are associated with it, most frequently antipsychotic medicines, benzodiazepines, beta-blockers. Never stop, pause, or change a prescribed medicine because of that; take the observation and the date it started to the person who prescribed it, who can weigh a review against what the medicine is doing for you.
When should I see someone about too tired for sex?
Sooner than most people do. Specifically and without waiting: Fatigue with unexplained weight loss, night sweats that are not menopausal, breathlessness, or new lumps needs assessment promptly.
What can I do about too tired for sex myself?
Ask for a blood test before assuming this is life rather than physiology — thyroid, iron, and glucose cover most of the treatable ground. Move intimacy out of the last hour of the day; for many couples that single change does more than anything else on this page. Treat the domestic load as part of the problem, because for a lot of people it is most of it.
Educational information about why a symptom happens — not a diagnosis, and not a way to work out what is wrong with you. Most of these changes have more than one cause at once, and the causes on this page overlap. Nothing here can examine you, look at your history, or run a test. Pain, bleeding, a lump, or a symptom that is new and unexplained always deserves assessment.