GLP-1 Medications: Side Effects and Concerns

Digestive Problems

Weight loss jabs such as Wegovy and Mounjaro have boomed in popularity, and so have reports of myriad side-effects. This week researchers have suggested GLP-1 medications could be associated with hair loss, adding to a long list of known gastrointestinal disturbances including nausea, vomiting, diarrhea, and constipation.

According to clinical trials, these symptoms are well documented, but they usually subside over time as the body adjusts. Experts attribute these side-effects to the mechanism of action of GLP-1 medications, which slow the progress of food through the digestive tract, slow stomach emptying, and affect signaling from the gut to the brain.

While common, these gastrointestinal symptoms are described in patient leaflets as very frequent, with some individuals experiencing them within weeks of starting treatment. Manufacturers note that while uncomfortable, most side-effects diminish after the first few months of use.

Eye Conditions

More than one eye condition has been flagged in relation to GLP-1 medications. A study last year revealed people with diabetes who use these drugs could face double the risk of developing age-related macular degeneration, a leading cause of vision loss among older adults.

In addition, reports based on adverse event reporting systems and matched cohort studies have suggested some GLP-1 medications may cause an eye disorder called non-arteritic anterior ischaemic optic neuropathy (NAION). This condition can result in sudden, permanent sight loss. Pharmaceutical companies accept this as a possible side-effect, noting it is mentioned in the patient leaflets of Wegovy.

However, experts stress that this adverse effect remains very rare and should not deter individuals from using GLP-1 medications if prescribed by their healthcare provider.

Pregnancies

The use of GLP-1 medications has sparked debates about unplanned pregnancies. While the exact mechanisms are not fully understood, some experts suggest that these drugs might interfere with contraceptive effectiveness or boost fertility due to weight loss benefits. A study published in 2023 found that while pregnancy rates among those using GLP-1 medications were similar to non-users, the risk of unintended pregnancies was significantly higher.

Experts point out that conclusive evidence is lacking since initial clinical trials excluded women who were pregnant or planning to become pregnant. The UK Medicines and Healthcare products Regulatory Agency (MHRA) has stated that GLP-1 medicines should not be taken during pregnancy or just before trying to get pregnant, as there is insufficient safety data to determine whether these medications can cause harm to the baby.

Similar warnings are present in patient information leaflets. The MHRA advises women of childbearing age to use effective contraception while on GLP-1 therapy and for at least three months after discontinuing it if they plan to conceive.

Hair Thinning

This week research suggested a possible link between hair loss and the use of GLP-1 medications in adults with type 2 diabetes. While not a new concern, patient leaflets for Mounjaro and Wegovy list it as a common side-effect.

Experts have previously called for further research in this area, noting that mechanisms remain speculative. One possible explanation is that hair loss is due to rapid weight loss and its associated metabolic changes and nutritional deficiencies.

Source: The Guardian