What the Zepbound® documents contain
A search of the three sets of tirzepatide product information for sexual, erectile and libido turned up only animal findings [1][3][4]. In rat fertility studies, tirzepatide did not affect sperm shape, mating, fertility or conception; female rats showed cycle changes that the label puts down to lower food intake and body weight [1]. Canada’s monograph notes that young rats given tirzepatide reached sexual maturity later, which it also attributes to slower weight gain [3]. None of this has been shown in people.
The human data that do touch on sex are indirect: listed reactions that affect energy, blood pressure or blood sugar, and pregnancy and contraception advice, which belongs on a separate page.
| Finding | Zepbound® | Placebo or comparison | Source |
|---|---|---|---|
| Fatigue, including weakness, lethargy and malaise | 5% to 7% by dose | 3% | US label, Table 1 [1] |
| Low blood pressure | 1.6% | 0.1% | US label, section 6.1 [1] |
| Low blood pressure in people also on blood pressure medicine | 2.2% | 1.2% without such medicine | US label, section 6.1 [1] |
| Blood sugar below 54 mg/dL in type 2 diabetes (SURMOUNT-2) | 4.2% | 1.3% | US label, section 5.7 [1] |
| Sexual side effects in people | Not listed | Not listed | US, Canada, EU [1][3][4] |
What studies in men report
The study closest to Zepbound® users is small. In Italy, 83 men with obesity and metabolic hypogonadism, low testosterone linked to excess weight, followed a reduced-calorie diet with daily walking and were allocated to tirzepatide, no medicine, or testosterone gel. After two months, the tirzepatide group had lost more weight and fat, and had higher testosterone and better scores on a standard erectile function questionnaire than both other groups [5]. The abstract does not describe randomisation, the groups differed at the start, and two months is short [5].
In men with type 2 diabetes, a records study using matched comparisons found a new erectile dysfunction diagnosis or erection-medicine prescription less often after starting tirzepatide than after starting sitagliptin, semaglutide or dulaglutide [6]. A 2026 systematic review on severe obesity reports that GLP-1 medicines raise testosterone and improve erectile function [11], though another review notes that the testosterone studies mostly involved liraglutide or semaglutide [9]. For men planning to become fathers, a 2026 review found no controlled tirzepatide study of semen or fertility and says these medicines should not be used as fertility treatments [9].
What is known for women
Evidence in women is very limited. One case report describes a 36-year-old woman with severe obesity who developed lower desire, genital dryness and difficulty reaching orgasm while taking tirzepatide; her symptoms eased when she stopped, returned when she restarted, and improved with sexual health support [7]. A single case cannot show how often this happens or prove the medicine caused it.
A 2026 review covering several weight-loss medicines reported encouraging findings for GLP-1 medicines in men, scarce direct data in women, and tirzepatide case reports hinting at sexual side effects; in most trials, sexual health was measured only as a secondary outcome [8].
Why sexual function might change on Zepbound®
Three layers, from best supported to least.
- Supported by the label. Tiredness and low blood pressure are both more frequent on Zepbound® than on placebo, and low blood pressure was more common in people also taking blood pressure medicine [1]. In people with diabetes, low blood sugar is more likely with insulin or a sulfonylurea [1], and the NIH notes that both high and low glucose can affect arousal [13].
- Proposed but not proven. A case report raises possible effects on hormones and nerve pathways, and a review describes several direct and indirect routes, but none has been measured in Zepbound® users [7][8].
- General medical knowledge. Weight change, energy, mood and body image all shape sexual life. MedlinePlus lists low testosterone, blood pressure medicines, nicotine, alcohol and stress among causes of erection problems [12].
The sleep apnea connection
Zepbound® is approved for moderate or severe obstructive sleep apnea when obesity is present [1][2]. The NIH lists sexual dysfunction or decreased libido among the symptoms of sleep apnea, alongside daytime sleepiness, fatigue and waking at night to urinate [10]. For people using Zepbound® for this reason, sexual difficulties may have been present before treatment, and any change during treatment has more than one possible explanation.
Diabetes is the other strong background factor. SURMOUNT-2, one of the two trials behind the label’s side-effect table, enrolled only people with type 2 diabetes, who made up a quarter of the pool [1]. NIDDK reports that more than half of men with diabetes develop erectile dysfunction, that low testosterone is more likely in older and overweight men with diabetes, and that women with diabetes may have low desire, vaginal dryness or painful sex [13].
Other causes to consider
MedlinePlus explains that most erection problems have a physical cause, such as clogged arteries, nerve disorders, blood pressure or heart medicines, low testosterone, nerve damage after prostate surgery, or nicotine, alcohol or cocaine use, and that stress, anxiety and relationship strain play a part too [12]. Erections during sleep or on waking suggest the cause is less likely to be physical [12].
For women, MedlinePlus lists diabetes, heart disease, nerve disorders, hormone problems and some medicines among physical causes, and work stress, anxiety, depression and relationship concerns among psychological ones [14]. Canada asks for monitoring of depression and unusual mood changes in people on Zepbound® [3], and low mood often affects desire.
What may help
MedlinePlus describes occasional sexual problems as common and advises seeing a provider when they persist for several months or upset you or your partner [14]. For erection problems it notes that lifestyle changes help many men, that couples who struggle to talk about it may benefit from counselling, and that several medical treatments exist [12]. NIDDK mentions that a vaginal lubricant, prescription or over the counter, may help with dryness [13].
One Zepbound®-specific caution: erection medicines carry their own warnings about low blood pressure, and MedlinePlus says never to combine them with nitroglycerin [12]. Because Zepbound® can also lower blood pressure [1], tell your prescriber about every medicine you take. If you take birth control pills, see the separate page on oral contraceptives, since Zepbound® affects how well they are absorbed [1].
Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Thoughts of harming yourself, or new, worse or worrying changes in mood | Your healthcare professional right away; emergency services in a crisis | Emergency | Canadian patient information [3] |
| A possible pregnancy while using Zepbound® | Your prescriber promptly; Zepbound® is stopped when pregnancy is recognised | Today | Label §8.1 [1]; Medication Guide [2] |
| Trouble getting or keeping an erection more than a quarter of the time | Your health care provider | At your next appointment | MedlinePlus [12] |
| Low desire, dryness, pain or trouble reaching orgasm that persists for months or upsets you | Your health care provider or gynaecologist | At your next appointment | MedlinePlus [14] |
| Light-headedness on standing while on blood pressure medicine | Ask your prescriber about a review | At your next appointment | Label §6.1 [1] |
