GLP-1s and Sex Drive: What Ozempic and Mounjaro Do to Libido in Men and Women

Nobody knows how often Ozempic, Wegovy, Mounjaro or Zepbound lowers sex drive, because no large trial has measured it. The one placebo-controlled test of desire gave dulaglutide to 26 healthy, normal-weight men for four weeks and found no change.^[1] Rodent studies point the other way: GLP-1 drugs cut sexual behavior in male and female animals.^[6][9] In people there are case reports, a few hundred adverse-event reports, and small studies in which men with obesity gained testosterone and better sexual function as they lost weight.^[10][17] None of the US labels lists a change in libido. The honest summary: a real effect in some people is plausible, its size is unknown, and for most people the more likely culprits are nausea, tiredness and eating far less.

What is known, and how well

The label position: silent

The words “libido,” “sexual,” “erectile” and “orgasm” do not appear anywhere in the current US prescribing information for Wegovy or Zepbound.^[20][21] The Ozempic and Mounjaro labels are equally silent,^[22][23] and so is Saxenda’s.^[24] Their adverse-reaction tables list effects reported by at least 2% of people on the drug and more often than on placebo. A change in desire is not on any of them.

Silence on a label is not proof of no effect. The registration trials did not ask about desire with a standard questionnaire, so an effect would have shown up only if participants raised it unprompted and investigators coded it. A 2026 review in Sexual Medicine Reviews makes the same point about every weight-loss drug class: sexual outcomes, where measured at all, were secondary endpoints.^[4] What the label does establish is that if low libido happens, it was not common or obvious enough to be recorded in trials of thousands of people.

The only placebo-controlled test of desire

A Swiss team at University Hospital Basel set out to test the reward theory directly. They enrolled healthy men aged 18 to 50, of normal weight, with normal testosterone and an active, satisfying sex life. Each man took weekly dulaglutide (Trulicity) for four weeks and placebo for four weeks, in random order, without knowing which was which. Desire was scored with the Massachusetts General Hospital Sexual Functioning Questionnaire.^[1]

Of the 26 men randomized, 24 finished. Desire scores did not differ between dulaglutide and placebo, and the confidence interval ran in both directions. Testosterone, LH, FSH and semen measures all stayed normal.^[1] That is a clean negative result, and it is narrow. It covers one drug, at one dose, for one month, in lean men who had no weight to lose and were not taking it for obesity. It says nothing about women, about semaglutide or tirzepatide at weight-loss doses, or about months of treatment and a large calorie deficit.

The reward-pathway theory, and why it is still a theory

GLP-1 receptors sit in brain areas that process reward, and the drugs reduce how much animals work for food, alcohol and other drugs. That is the basis of trials such as the one on semaglutide for alcohol use disorder. Sex runs through overlapping circuits, so a group at the University of Gothenburg tested it in rodents. The results below are animal results.

• Male mice, no sexual experience. An injection of exendin-4, a short-acting GLP-1 drug, reduced mounting but did not change the mice’s preference for females. Infused into a brainstem area that relays gut signals, it raised dopamine turnover and serotonin in a reward region and raised the stress hormone corticosterone, while testosterone did not change.^[6] Infusions into some parts of the reward circuit reduced courtship behavior and others did not.^[7]
• Experienced male mice. Exendin-4 cut intromissions and ejaculations. Liraglutide and dulaglutide, the longer-acting drugs closer to what people take, did not change sexual behavior.^[8]
• Females. In female rats, exendin-4 reduced time spent with males and several sexual behaviors. Female mice on liraglutide or dulaglutide spent less time near a male. The authors called the effects drug-specific and species-specific.^[9]

Two research groups have built on this a theory for people. One proposes that GLP-1 drugs raise serotonin activity at a receptor called 5-HT2C, which in turn damps desire; the authors present it as a theoretical model, not a finding.^[5] A Mayo Clinic review of midlife women suggests the drugs may suppress desire and arousal through dopamine and serotonin signaling, and adds that “systematic clinical evidence remains limited.”^[3] A third review sums up the gap plainly: the animal data and the human data do not yet agree.^[2] Every mechanism on offer for people is inference from animals.

Adverse-event reports: a few hundred, no rate

FDA’s Adverse Event Reporting System (FAERS) collects reports from patients, doctors and manufacturers. Anyone can file one, nobody checks that the drug caused the problem, and the number of people taking the drug is unknown. Counts show that people noticed something and reported it. They cannot give a rate, and they cannot show cause.

Those are small numbers against tens of thousands of reports per drug.^[12] Some reports did not record sex, so the two columns do not add up. A Stanford analysis of FAERS through early 2024 pooled orgasm problems, erectile dysfunction and decreased libido in men on six GLP-1 drugs and found 182 reports. The reporting odds ratio was 0.41: these problems were reported less often for GLP-1 drugs than for the database as a whole. That is a measure of reporting, not of risk, though the authors judged overall risk low.^[10] A 2026 FAERS study found erectile dysfunction reported somewhat more often than expected with semaglutide, but the same was true of two unrelated diabetes drugs, sitagliptin and dapagliflozin, and the authors stressed that this does not establish cause.^[11] Diabetes itself is a well-established cause of erectile dysfunction, which is one reason these signals are hard to read.^[11]

Women: almost no data

No published trial has measured sexual desire in women taking semaglutide or tirzepatide. Reviews in 2026 describe the effect on female sexual function as “largely uncharacterized” and direct evidence in women as limited.^[3][4] What exists in the published record is mainly two case reports:

• Tirzepatide. A 36-year-old woman with severe obesity reported falling desire, genital dryness and difficulty reaching orgasm while on tirzepatide. Her score on the Female Sexual Function Index, where higher is better, was 12.7 on the drug, 28.7 after stopping and 14.7 after restarting.^[14] A stop-and-restart pattern is the strongest kind of evidence a single case can give. It is still one person.
• Unnamed GLP-1. A Cleveland team reported a woman who lost the ability to orgasm after starting a GLP-1 drug and proposed mechanisms, including reduced blood flow and brain signaling, without testing any of them.^[13]

The Mayo review notes the irony: weight loss by diet or surgery tends to improve women’s sexual function, so if GLP-1 drugs lowered desire, it would run against the weight loss rather than with it.^[3] The authors recommend that clinicians ask about sexual function before and during treatment. For women going through menopause, when desire often changes anyway, the timing question is covered in GLP-1s after menopause. For women with polycystic ovary syndrome, where testosterone and weight are both part of the condition, see GLP-1s for PCOS.

Men: weight loss and testosterone push the other way

In men, excess weight can suppress testosterone, a condition called functional hypogonadism, and losing weight can partly reverse it.^[19] The small trials in men with obesity-related low testosterone fit that pattern:

• Liraglutide vs testosterone gel, 30 men, 16 weeks. Total testosterone rose on both: 5.9 nmol/L on the gel and 2.6 nmol/L on liraglutide. Sexual function improved on both. The liraglutide group lost 7.9 kg; the gel group lost 0.9 kg.^[17]
• 110 younger men with low testosterone and obesity, 4 months. Men given liraglutide had better erectile function scores than at baseline and than men on gonadotropins or testosterone gel. Treatment was assigned by whether the men wanted children, not at random.^[18]
• A 2026 systematic review of 29 studies found GLP-1 drugs and tirzepatide raised total testosterone by an average of 2.5 to 5.2 nmol/L in men with obesity-related low testosterone, mostly through weight loss. The randomized trials had 12 to 42 men each.^[19]

None of these used a desire-specific questionnaire as the main outcome. The fuller account of testosterone, sperm and the comparison with testosterone replacement is in GLP-1s, testosterone and male fertility. One study in that literature also found a rise in sex hormone-binding globulin on liraglutide,^[18] which binds testosterone; one hypothesis paper lists that rise among the factors that could pull desire down even as total testosterone goes up.^[5]

Can a GLP-1 increase libido?

Some people report exactly that. In a study of about 5,900 Reddit threads about GLP-1 drugs, researchers found posts in which users described higher sex drive after starting treatment, often credited to weight loss and better body image.^[15][2] FAERS holds a handful of increased-libido reports as well.^[12] Social-media posts are self-selected and unverified, so they show the claim exists, not how often it is true.

The better data point comes from a randomized trial. In the SCALE trial of liraglutide 3.0 mg (Saxenda), more than 2,700 participants filled in a weight-related quality-of-life questionnaire with a “sexual life” section. That score improved by 8.5 points on liraglutide and 6.0 on placebo, on a 0 to 100 scale, and all sections improved more on the drug.^[16] The authors called the quality-of-life results exploratory, and many people already scored at the top of the sexual-life scale at the start. The questionnaire asks how weight affects sex life, not about desire directly. Still, it is the only large randomized measure that touches sex at all, and it moved in the right direction.

The ordinary explanations come first

Before blaming a reward circuit, rule out the plain causes. They are on the label, and they are common:

• Nausea. In the Wegovy weight-loss trials 44% of people on the drug had nausea against 16% on placebo.^[20] On Zepbound it was 25% to 29% depending on dose, against 8%.^[21] Feeling sick does not make anyone want sex.
• Fatigue. About one in ten people on Wegovy 2.4 mg reported fatigue, roughly twice the placebo rate.^[20] Causes and fixes are in why GLP-1s make people tired.
• Eating very little. When appetite collapses, energy and mood can drop with it. This is most likely during dose increases, when the side effects above also peak.
• Everything else that changed. Stress, sleep, relationship changes, a new diagnosis or another new medicine started around the same time all affect desire. A drop that starts the week of a dose increase and fades as nausea settles points to side effects. A drop that persists at a stable dose, with no nausea, is a more interesting signal.

When to raise it with a prescriber

Raise it. Reviews of this field repeatedly note that nobody asks, so nobody counts.^[3][5] Specific reasons to bring it up promptly:

• Desire has stayed low for several weeks at a steady dose, after the nausea of the last increase has passed.
• It comes with low mood, loss of interest in other things you enjoy, or poor sleep. Those deserve attention on their own.
• It comes with erection problems, vaginal dryness, or pain with sex. Each has its own causes and treatments.
• You have both a desire change and symptoms of low testosterone, or you are a woman whose periods have changed.

Useful things to discuss: whether a lower maintenance dose would hold your weight loss, whether a blood test for testosterone makes sense, and whether any other medicine could be responsible. Keep taking the drug as prescribed while you sort it out; any dose change should be the prescriber’s call. If you want your experience on record, you or your prescriber can file a report with FDA MedWatch. Drugs sold for low desire are a separate question: the evidence on PT-141 (bremelanotide) and kisspeptin is reviewed on their own pages.