Surgeon warns weight loss shots may weaken birth control pills

By Lauren Wilkin

A doctor who specializes in obesity management and weight loss surgery is warning women on weight loss shots that their contraceptive pill can be "less effective" if you take GLP-1s.

"If you rely on an oral birth control pill, you need to use a backup method like condoms," Dr. Wiljon Beltre says, a board-certified and fellowship-trained bariatric and metabolic surgeon.

The impact of weight loss shots on the contraceptive pill does depend on the type of GLP-1 you use, however.

"Wegovy itself does not directly block the contraceptive pill from working in your gut," says Dr. Beltre, who specializes in advanced weight loss procedures.

"That specific absorption warning actually applies to drugs like Mounjaro and Zepbound.

"The real issue with Wegovy is the side effects, as if you take your daily pill and then throw up 2 hours later due to nausea, your body wouldn't have absorbed it yet.

"It's the same thing as missing a pill.

"Also if you have severe diarrhea for a couple of days, those hormones are flushing right through your system before they can do their job."

The doctor said the same problem is relevant for those taking Saxenda or Victoza, too.

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Another important factor to consider is the extreme and fast weight loss, says the doctor.

"If you're someone with obesity, losing 15 to 20% of your body weight can reset your hormones.

"Women with PCOS or severe obesity who thought they were infertile can suddenly start ovulating again, giving a massive boost in natural fertility.

"Combined with a birth control pill that just got thrown up, it's the perfect storm for an unplanned pregnancy."

The doctor advices to switch to an IUS, patch or implant if you get frequent nausea from your weight loss shot.

As for Mounjaro, Dr. Beltre says there's even greater issue.

"Mounjaro can pose a direct absorption issue for birth control pills.

"This is because it targets two gut hormones instead of one which slows the emptying of the stomach a lot more, especially when you're starting out or increasing the dose.

"The delay in digestion can drop the peak levels of contraceptive hormones that get absorbed into your bloodstream by around 20%, which means the pill doesn't hit your system quickly or strongly enough to guarantee full protection."

For this reason, the doctor says that if you rely on an oral birth control pill, you need to use a backup method like condoms for four full weeks after your first shot, and for four full weeks after every single dose increase.