Unregulated peptide injections may carry higher risks for women
Researchers warn that gray-market peptides sold for wellness uses may pose added hazards because of sex-based differences in hormones, immunity and body composition.
By Priya Raghavan · Science Reporter
3 min read
Unregulated peptides promoted online for fat loss, muscle gain and anti-aging may pose particular dangers for women, according to Adam Taylor and Michelle Swainson writing in The Conversation. They said the products are often sold without the testing, licensing and dose controls used for approved medicines, leaving users with limited information about safety.
Taylor and Swainson said the concern is not only that these products are unregulated. They wrote that women and men can respond differently to drugs, and that those differences may matter more when people inject substances whose strength and contents are uncertain.
Why women may face added risk
According to the researchers, women are about 1.5 to two times more likely than men to have an adverse drug reaction. They said part of that difference reflects prescribing patterns: women more often take prescription medicines, live longer on average and are more likely to have conditions that require long-term treatment, including osteoporosis, lupus and rheumatoid arthritis.
That can raise the chance of interactions before sex-based biology is considered, Taylor and Swainson wrote. They also pointed to differences in drug breakdown and clearance, immune responses and hormone patterns as factors that may change how women react to untested peptide products.
The researchers said the menstrual cycle depends on a tightly controlled hormonal signaling system involving the brain and ovaries. Peptides that raise hormone levels from outside the body may interfere with that system, they wrote.
Taylor and Swainson cited ipamorelin and CJC-1295, two peptides marketed for muscle growth and anti-aging, as examples. They said these substances increase growth hormone and IGF-1, and can keep levels elevated for days; they linked that sustained increase to swelling, fluid retention, hormonal disruption, ovarian effects and a higher risk of miscarriage.
Cancer and pregnancy concerns
The Conversation article also highlighted TB-500, a synthetic version of part of thymosin beta-4, a peptide naturally involved in tissue repair. Taylor and Swainson said thymosin beta-4 has been detected in several cancers, including breast cancer cells and some common lung cancers, while TB-500 is marketed for tissue repair, inflammation reduction and flexibility.
They noted that lung cancer rates among American women under 65 surpassed those among men in the same age group in 2021, and that women are often diagnosed later than men. In that context, they warned against treating a peptide linked to cancer cells as low-risk.
The researchers also discussed GHK-Cu, a copper-containing peptide used in some anti-aging skin creams. They said laboratory studies suggest it may support collagen production and skin elasticity when used on skin, but injection changes the risk because injected products bypass the skin barrier and digestion.
According to Taylor and Swainson, unregulated injectable peptides create uncertainty over the amount delivered into the body. They said this is a particular concern for women who could become pregnant because it is unknown whether these peptides can cross the placenta.
They wrote that excess copper can cause abdominal pain, nausea and vomiting. In pregnancy, they cited research finding that each additional microgram per milliliter of copper in maternal blood was associated with a 30% higher risk of premature birth and an average pregnancy shortening of 1.6 days.
Injection site and dosing issues
Taylor and Swainson said anatomy may also affect risk. Women tend to carry more fat around the hips, thighs and buttocks, which can mean less abdominal fat to cushion stomach injections, they wrote.
They also said men are generally heavier, have larger body surface area and have more body water, which can affect how a dose spreads through the body. For a woman of similar age and weight, the same dose may have stronger effects, according to their analysis.
The researchers concluded that gray-market peptides remain risky for anyone using them, with added uncertainties for women because of hormonal, immune and anatomical differences. They said properly controlled human studies are needed before users can know how these products are likely to affect the body.
This story draws on original reporting from Medical Xpress.