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Hormonal conditions
Thyroid hormone sets the pace of nearly every system, so an underactive thyroid produces fatigue, low mood, and low desire together, while an overactive one produces anxiety, poor sleep, and exhaustion that lands in the same place. Both affect the sex hormones downstream. The reason it matters disproportionately is that it is one of the cheapest blood tests there is and one of the least often ordered for this complaint.
See someone about this if
Editorial categories, not percentages, and never a prediction about you. Each links to the fuller picture of that change.
Wanting sex less often, or losing the spontaneous interest that used to arrive on its own. This is the effect people most often assume is psychological and most often is not only psychological.
Sex stops happening because there is nothing left in the tank by the time there is an opportunity. A real medicine effect, not a motivation problem.
Erections that are slower, softer, or do not hold. Because this depends on blood vessels and nerves, it can also be an early signal of something cardiovascular — which is why it is worth a clinical conversation rather than only a product.
The body responds less, or much more slowly, even when the interest is there. Blood flow, nerve signalling, and hormone levels all feed this, and medicines can act on any of the three.
Less natural lubrication, a tight or raw feeling, or discomfort that arrives during rather than before sex. Medicines cause this either by drying mucous membranes generally or by lowering oestrogen.
Condition or treatment?
Thyroid replacement usually improves all of this once the level is right, so a persisting symptom often means the dose has not settled rather than that the thyroid was a red herring. Lithium can cause an underactive thyroid in the first place, which is why it appears here as well as on the medicines side.
For almost every condition on this site, the condition and the medicines that treat it both affect sex — by different mechanisms, on different timescales, and with different answers. Being able to say which half you are asking about is the single most useful thing you can bring to an appointment, and it is the thing patients are least often given.
Never stop, pause, reduce, or change a prescribed medicine because of anything on this page. Some of the medicines listed here are dangerous to stop suddenly, and the condition being treated does not pause while you experiment. Everything here exists to make your next conversation with a prescriber more specific — not to replace it.
Thyroid hormone sets the pace of nearly every system, so an underactive thyroid produces fatigue, low mood, and low desire together, while an overactive one produces anxiety, poor sleep, and exhaustion that lands in the same place. Both affect the sex hormones downstream. The reason it matters disproportionately is that it is one of the cheapest blood tests there is and one of the least often ordered for this complaint.
The effects reported most often are lower sexual desire and fatigue or sedation getting in the way. Reported does not mean inevitable — the picture varies a great deal between people, and most people have more than one thing contributing at once.
Thyroid replacement usually improves all of this once the level is right, so a persisting symptom often means the dose has not settled rather than that the thyroid was a red herring. Lithium can cause an underactive thyroid in the first place, which is why it appears here as well as on the medicines side. Timing is the most useful clue you have: an effect that appeared within weeks of starting or changing a treatment points at the treatment, while one that predates it points at the condition. Never stop, pause, or change a prescribed treatment to find out — take the timeline to the person who prescribed it.
The classes commonly used here that carry documented sexual effects are beta-blockers and lithium. Each has its own profile, so which one you are on matters — and that is a prescribing conversation, never a reason to stop anything.
Ask for the actual numbers rather than 'normal' — a result at the edge of the range with symptoms is a different conversation from one in the middle. Give a dose change a full cycle before judging its effect on energy and desire.
Sooner than most people do, and specifically without waiting: Fatigue with unexplained weight change, feeling cold all the time, or hair loss should prompt thyroid testing rather than a product.
Educational information about what a diagnosed condition tends to do — not a diagnosis, not a way to work out whether you have something, and not advice about your treatment. Conditions on this page overlap, and most people with a long-term condition have more than one thing affecting them at once. Nothing here can examine you or run a test. Pain, bleeding, or a new and unexplained symptom always deserves assessment.