Christine Smith-Reed had tried everything to lose weight. She hired a nutritionist, committed to a rigorous gym routine, and eventually underwent stomach reduction surgery, yet the pounds kept coming back and her body grew increasingly resistant to insulin. At 50, the Oregon salon owner turned to tirzepatide, the active ingredient in weight loss medications Mounjaro and Zepbound, hoping it would finally help her stabilize blood sugar and maintain a healthy weight. She got the body she had been working toward for years. But that was not all she lost.
“Sex suddenly stopped interesting me at all,” Smith-Reed told The New York Post. Her intimate life with her husband had gone through its natural ups and downs across 17 years of marriage, but she had typically been the one keeping the spark alive. After starting the medication, her libido disappeared entirely. “I would participate, but I either wouldn’t reach orgasm or it would take an enormous amount of effort. I felt guilty because it had nothing to do with my husband. I literally thought something was wrong with me,” she said. The fallout extended beyond the bedroom. “When you go from a very active sex life to none at all, silence sets in. There were cold looks and hurt feelings, probably on both sides.”
GLP-1 medications work by mimicking hormones released in the gut after eating, helping to regulate appetite and blood sugar, but their influence on the brain can produce unexpected outcomes. According to Dr. James Chao, co-founder of VedaNu Wellness medical center in San Diego, the drugs can dial down the brain’s pleasure-seeking signals, leaving sexual motivation with nowhere to go. “Fewer signals are being sent to the brain to seek pleasure, so sexual motivation simply disappears,” he explained. Still, he was careful to note that the effect is far from universal.
For some patients, Dr. Chao says, the experience runs in the opposite direction entirely. Losing weight makes movement comfortable again, clothes fit better, and people can look in the mirror without distress. “That visual dopamine boost, combined with reduced cortisol, can actually send some people’s libido through the roof,” he said. CJ Rock, a 47-year-old woman, recognized that pattern from her past. “Previously when I lost weight, I got this injection of confidence, almost like dopamine, and it made me crave sex more,” she explained. But when she began taking tirzepatide, her drive plummeted despite the weight coming off. “My sex drive was normal, roughly two to three times a week. I had desire and need,” she said, and then it was simply gone.
In seven months on the medication, Rock shed 70 pounds and felt genuinely good in her body. But when her fiancé tried the things that had always worked before, her body simply did not respond. “I was almost numb to it. There were nights I wondered what was wrong with me.” Dr. Chao explained that rapid weight loss, the kind GLP-1 drugs tend to produce, can push the body into a kind of energy-conservation mode. “Because libido is categorized as a ‘want’ rather than a ‘need,’ the brain will often suppress it until things return to balance,” he said. For both Rock and Smith-Reed, the picture was further complicated by perimenopause, making it difficult to untangle the effects of hormones, aging, and medication. “It’s really hard because when you enter perimenopause, sex drive is one of the first things to go,” Rock noted.
Nathalia Souza, a 37-year-old woman from New Jersey, had no hormonal transition to factor in, yet she experienced the same sharp drop. She started tirzepatide after losing only about 29 pounds across three years of dieting and exercising on her own, and the medication helped her shed another 22 pounds over seven months. The results felt like a success in almost every way except one. “I had a very high sex drive, and about two months into the treatment I noticed I had no desire whatsoever,” Souza said. Before the medication, she and her husband were intimate four to five times a week. Five months later, she found herself pulling away from even a kiss. “I told him: ‘No, stop, I don’t even want you to kiss me,’” she recalled. The shift forced her to ask whether the trade-off was worth it. “That’s where I draw the line. I will not lose my marriage over this,” she decided. After trying supplements including vitamin D, magnesium, and creatine with no success, she eventually found a supplement that she says helped restore her desire.
For Smith-Reed, relief came in the form of a synthetic peptide known as PT-141, or bremelanotide, which works by stimulating receptors in the brain to activate sexual desire. After her first injection, she felt the difference. “It’s not that my sex drive went wild, but I had no trouble reaching orgasm. Multiple times. It was like surfacing after nearly drowning. Like I wasn’t broken,” she said. Rock found her answer in patience. “After being on the medication for a while, my sex drive did come back, though I wouldn’t say it’s very strong. I think my body just got used to the drug and adjusted over time,” she said.
Doctors generally advise patience as a first step. “I tell patients that libido changes, if they occur, are usually not permanent,” said Dr. Fernando Ovalle Jr., an obesity medicine specialist. “In many cases, things normalize as the dose stabilizes and the body adapts.” A spokesperson for Eli Lilly, the manufacturer of tirzepatide, stated that patient safety remains the company’s top priority and encouraged anyone experiencing side effects to consult their physician. Dr. Ovalle added that the wide range of experiences points to a simple truth: researchers are still learning how these medications interact with both the body and the brain. “We don’t yet have high-quality studies examining libido. Most of what we know comes from real patient experiences rather than formal research,” he acknowledged. For Smith-Reed, the message she most wants to pass on is one she needed to hear herself. “I want every woman to know she is not broken. It’s a side effect of the medication, and like any other, it doesn’t affect everyone. But if it affects you, know that you haven’t lost something forever. There are ways to come back.”
The GLP-1 receptor in the brain is also found in areas that regulate dopamine release, mood, and reward processing, which is part of why researchers believe these drugs may eventually be explored for addiction treatment. Tirzepatide actually targets two gut hormone receptors simultaneously rather than one, making it a so-called dual agonist and technically distinct from older GLP-1 drugs like semaglutide, even though they are often grouped together in conversation. PT-141, the peptide Smith-Reed used to reclaim her libido, was originally developed as a potential tanning agent before researchers stumbled onto its rather more interesting effect on sexual arousal.
Have you or someone you know experienced unexpected side effects from a weight loss medication? Share your thoughts in the comments.
