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GLP-1s for Women: What the Trials Show, What Compounded Really Means, and the Birth-Control Catch

Semaglutide and tirzepatide produced 15% to 21% average weight loss in their main trials, and stopping led to regain. Compounded versions are not FDA-approved, and tirzepatide can make the pill less reliable.

By Kymata Health editorial teamLast verified October 10, 2026

Medical review pending. Written by our editorial team from the studies and documents cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • Semaglutide 2.4 mg weekly produced a 14.9% average weight loss at 68 weeks vs 2.4% on placebo in STEP 1 [1].
  • Tirzepatide produced 15.0% (5 mg) to 20.9% (15 mg) average weight loss at 72 weeks vs 3.1% on placebo in SURMOUNT-1 [2].
  • When people switched from semaglutide to placebo after 20 weeks, they regained 6.9% of body weight over the next 48 weeks; 79% of that trial's participants were women [3].
  • Compounded GLP-1s are not FDA-approved, and the FDA warns against any company claiming its compounded drug is the same as an approved one [4].
  • Tirzepatide can reduce how well birth-control pills work: its label says to switch to a non-oral method or add a barrier method for 4 weeks after starting and after each dose increase [5].

Guides in this hub

  1. Semaglutide vs Tirzepatide: How Much Weight the Trials Showed, and What Happens When You StopThe headline numbers come from 68- to 72-week trials with diet and activity support. The less-quoted number is what happened when people stopped.
  2. Compounded Semaglutide and Tirzepatide: What the FDA Actually Says, and the Red Flags to CheckCompounded GLP-1s are legal in limited circumstances but are not FDA-approved, and the FDA has warned companies that market them as the same thing as the brand-name drugs. Here is the checklist.
  3. GLP-1s, the Pill and Pregnancy: The Label Warnings Women Need Before StartingTirzepatide can make oral birth control less reliable at the start and after each dose increase. Semaglutide needs a 2-month washout before trying to conceive. Both labels say to stop when pregnancy is recognized.

How well they work

The brand-name drugs were tested in large placebo-controlled trials alongside diet and activity advice. In STEP 1, half of people on semaglutide lost 15% or more of their body weight by week 68 [1]. In SURMOUNT-1, half of people on 10 mg tirzepatide and 57% on 15 mg lost 20% or more by week 72 [2].

Nausea, diarrhea, vomiting and constipation were the most common side effects, mostly during dose increases [1][2]. Our dose scheduler maps the standard escalation steps.

Brand-name vs compounded

Wegovy (semaglutide) and Zepbound (tirzepatide) are FDA-approved for weight. Compounded semaglutide and tirzepatide are made by pharmacies and are not reviewed by the FDA for safety, effectiveness or quality before they are sold [4]. The FDA has received hundreds of adverse-event reports for each, including dosing errors with multi-dose vials, and says salt forms such as semaglutide sodium should not be used in compounding [4].

That does not make every compounded product unsafe, but it does mean the brand-name trial results above were not produced with compounded drugs. Our compounded GLP-1 guide lists the FDA's red flags, and our GLP-1 cost guide compares published prices.

What is different for women

Two label points matter most. Tirzepatide slows stomach emptying enough to reduce how well oral contraceptives are absorbed, largest after the first dose [5]. Semaglutide should be stopped at least 2 months before a planned pregnancy because of its long half-life [6]. Our birth control and pregnancy guide has the details.

Partners we link to

Paid links: we earn a commission if you buy through these, at no extra cost to you. It never changes what the evidence sections say. Affiliate disclosure.

  • FoundPaid linkWeight care with named board-certified clinicians: brand-name GLP-1 prescriptions (medication billed separately, insurance accepted) or compounded semaglutide and tirzepatide, which are not FDA-approved. LegitScript certified.See Found's weight plans
  • GalaPaid linkWomen-focused online weight care: compounded semaglutide or tirzepatide (not FDA-approved) at a published flat $179/mo on a yearly subscription, visits and shipping included (checked Oct 8, 2026). LegitScript certified.See Gala's GLP-1 plans

Regulatory and legal notes

  • Compounded semaglutide and tirzepatide are not FDA-approved; the FDA advises that compounded drugs be used only when an FDA-approved drug cannot meet a patient's medical need [4].
  • On September 9, 2025 the FDA sent Hers warning letter 716825, citing its website claim of a "weekly injectable GLP-1 with the same active ingredient as Ozempic and Wegovy" as false or misleading for compounded semaglutide [7].
  • On March 3, 2026 the FDA announced 30 more warning letters to telehealth companies over compounded GLP-1 marketing, citing claims implying sameness with FDA-approved products and branding that obscures who compounds the drug [8].
  • Retatrutide and cagrilintide cannot be used in compounding under federal law, and products labeled "for research purposes" are not legal for human use [4].

Other names you will see

Listed for completeness. We have no paid relationship with these brands and do not link to them.

  • Hers: Sells compounded semaglutide; see the 2025 FDA warning letter above.
  • Willow: Women-focused online program that prescribes compounded semaglutide and tirzepatide (not FDA-approved); its site lists plans from $299 a month (October 2026). Not vetted by us.

References

  1. [1]Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med, 2021. PMID 33567185
  2. [2]Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med, 2022. PMID 35658024
  3. [3]Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity: The STEP 4 Randomized Clinical Trial. JAMA, 2021. PMID 33755728
  4. [4]FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (content current as of 10/01/2026). U.S. Food and Drug Administration, 2026.
  5. [5]ZEPBOUND (tirzepatide) injection: prescribing information. U.S. Food and Drug Administration (Drugs@FDA), 2026.
  6. [6]WEGOVY (semaglutide) injection and tablets: prescribing information. U.S. Food and Drug Administration (Drugs@FDA), 2026.
  7. [7]Warning letter to Hims & Hers Health, Inc. dba Hers, MARCS-CMS 716825. U.S. Food and Drug Administration, 2025.
  8. [8]FDA Warns 30 Telehealth Companies Against Illegal Marketing of Compounded GLP-1s (March 3, 2026). U.S. Food and Drug Administration, 2026.

Dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Prescription options need a licensed clinician. Talk to your clinician or pharmacist before starting anything new, especially if you take prescription medicines, are pregnant or breastfeeding.

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