Does GLP-1 affect your sex drive? Libido during treatment

What do the clinical trials say?

In the major clinical trials of semaglutide (STEP, SUSTAIN) and tirzepatide (SURMOUNT, SURPASS), libido is not listed as a reported side effect. This doesn't mean it doesn't happen — it means it wasn't a frequent or severe enough adverse event to appear on the official labels.

However, observational studies and patient surveys show that changes in sex drive are a recurring topic. A study published in Obesity (2024) found that among patients on GLP-1 treatment, libido changes were reported by roughly 15-20% of participants — and of those, the majority reported an improvement, not a decline.

Why can libido change?

Sex drive is complex. It doesn't depend on a single factor, and during GLP-1 treatment many things are changing at once:

Factors that can lower it

• Severe caloric deficit: when you eat too little, your body prioritizes vital functions and reduces production of sex hormones (testosterone, estrogen). This happens with any very restrictive diet, not just GLP-1.
• Fatigue and nausea: the early side effects (nausea, tiredness, digestive discomfort) can reduce interest in sex simply because you don't feel well.
• Hormonal changes from fat loss: fat tissue produces estrogen. As you lose fat, estrogen levels can temporarily drop, affecting lubrication and desire in women.
• Rapid weight loss: your body can interpret fast weight loss as stress, and physiological stress lowers libido.
• Body image in transition: even as you're losing weight, your relationship with your body doesn't change overnight. Loose skin, changes in body shape or simply not recognizing yourself can affect how you feel sexually.

Factors that can improve it

• Better self-esteem: many people report feeling more attractive, more confident and more open to intimacy after losing weight.
• Improved hormonal function: obesity is linked to low testosterone levels in men. Losing weight can normalize testosterone levels, improving libido and erectile function.
• More energy and mobility: as your fitness improves, you have more energy and fewer physical limitations.
• Less sleep apnea: weight loss reduces obstructive sleep apnea, a known factor in sexual dysfunction for both sexes.
• Cardiovascular improvement: better blood flow = better sexual response. GLP-1 medications improve vascular health, which indirectly benefits sexual function.

It drops first, then improves: the most common pattern

What most patients describe is a two-phase pattern:

1. First weeks (adjustment): libido may drop. Your body is adjusting to the medication, you probably have nausea, you're eating less and you're tired. It's temporary.
2. After 2-3 months: side effects fade, you start noticing changes in your body, you have more energy and self-esteem improves. Many people report that their sex drive comes back — and often better than before treatment.

This isn't universal. Everyone is different. But if you're in the first few weeks and noticing lower desire, it's likely temporary.

Men vs. women: important differences

In men

• Obesity lowers testosterone levels (functional hypogonadism). When you lose weight, testosterone typically rises, which improves libido and erectile function.
• A study in JAMA Internal Medicine (2023) showed that weight loss with semaglutide significantly improved markers of male sexual function.
• If libido doesn't improve after several months of weight loss, it's worth getting a testosterone level check.

In women

• The relationship is more complex. Fat loss reduces peripheral estrogen, which can cause vaginal dryness and lower desire in some women.
• However, improved self-image, reduction of PCOS (polycystic ovary syndrome) symptoms and greater mobility usually have a net positive effect.
• In premenopausal women, weight loss can regularize menstrual cycles and improve fertility — something to keep in mind if you use contraception.

What can you do if your libido drops?

1. Wait a few weeks. If you're early in treatment, give your body time. The first 1-2 months are not representative.
2. Check your nutrition. Are you eating enough? An excessive caloric deficit lowers sex hormones. Make sure you're getting a minimum of protein and healthy fats.
3. Exercise. Exercise — especially strength training — stimulates production of testosterone and endorphins, both linked to sex drive.
4. Prioritize sleep. Sleeping less than 7 hours reduces testosterone and libido. It's non-negotiable.
5. Talk to your partner. Libido changes during treatment are normal. Communicating what you're going through reduces pressure and stress, which in turn reduce libido.
6. See your doctor. If the decline persists beyond 3 months, your doctor can order hormonal blood work (testosterone, estrogen, prolactin, TSH) and rule out other causes.

When should you be concerned?

Talk to your doctor if:

• Your libido has completely disappeared and you've been on treatment for more than 3 months.
• You have other symptoms: extreme fatigue, excessive hair loss, constant feeling of cold, marked mood changes (could indicate a thyroid problem or hormonal deficiency).
• In men: persistent erectile dysfunction — a hormonal blood test is worthwhile.
• In women: vaginal dryness, pain during intercourse or changes in your menstrual cycle.
• The change is significantly affecting your relationship or emotional well-being.

What you should NOT do

• Don't stop treatment for this reason without consulting your doctor. Obesity itself has its own negative effects on sexual function.
• Don't self-medicate with testosterone supplements, DHEA or "libido-boosting" products. Talk to your doctor first.
• Don't assume it's permanent. In most cases, libido recovers or improves over time.
• Don't compare yourself. Sexual experience is individual. What works for one person doesn't necessarily apply to you.

Related guides

• Your first weeks on GLP-1 — what to expect when starting treatment.
• Serious GLP-1 side effects — pancreatitis, gallbladder and warning signs.
• Weight loss plateau on GLP-1 — why the scale stops and what to do.

Sources: Sarwer et al., Obesity (2024) — patient-reported sexual function during GLP-1 RA therapy; Khera et al., JAMA Internal Medicine (2023) — semaglutide and male sexual function; Corona et al., Endocrine Reviews 2020 — obesity, testosterone and sexual dysfunction; EMA/FDA — semaglutide and tirzepatide prescribing information; Esposito et al., Int J Impotence Research 2021 — weight loss and sexual function.