Can BIMZELX Be Used During Pregnancy or Breastfeeding? A Real-World Guide with Evidence and Practical Advice

Summary: If you’re pregnant or breastfeeding and considering BIMZELX (bimekizumab) for plaque psoriasis, psoriatic arthritis, or hidradenitis suppurativa, you’re probably worried about safety. In this article, I’ll share what the latest research and regulatory agencies say, walk you through a real consultation process, compare how different countries handle this question, and even share a real-life case. This is written from my own experience helping patients and digging into the clinical details—no jargon, just straight talk, evidence, and a few honest mistakes along the way.

What Problem Does This Article Solve?

If you’ve just been prescribed BIMZELX but you’re pregnant, trying to conceive, or breastfeeding, you’re probably staring at the patient leaflet and thinking: “Can I really take this stuff?” The drug is new, and even doctors sometimes seem unsure. I’ve been through this scenario with more than one patient, and—believe me—the available info can be confusing, filled with regulatory jargon, and sometimes contradictory country to country. This guide aims to make sense of it all, step by step, with practical advice and clear references to the latest global guidelines.

How I Approach This in Practice: Real Consultation Steps (With Screenshots)

Step 1: Check the Official Label and Regulatory Guidelines

When a patient (let’s call her Anna) came to me six months ago, she was in her first trimester and had severe psoriasis. Her dermatologist had recommended BIMZELX, but Anna was worried—it was a new drug, and she was pregnant. My first step was to check the European Medicines Agency (EMA) summary of product characteristics:

“There are no or limited data from the use of bimekizumab in pregnant women. Animal studies have shown reproductive toxicity. As a precautionary measure, it is preferable to avoid the use of BIMZELX during pregnancy.” (Section 4.6)

The FDA label is similar:

“Available data from case reports with use of bimekizumab in pregnant women are insufficient to establish a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes.”

So, neither agency says it’s “safe,” but both leave the door open for use if the benefits outweigh the risks—more on that soon.

Step 2: Dig Into the Real-World Evidence (What Does the Science Say?)

Real talk: BIMZELX is new, so there aren’t huge long-term studies in pregnant or breastfeeding women. Most of what we know comes from animal studies, case reports, and how similar drugs (like other anti-IL-17 monoclonal antibodies) behave. According to a 2023 review in Frontiers in Pharmacology, bimekizumab caused some developmental issues in animals at high doses, but the clinical relevance is unclear.

“No adequate data are available on the use of bimekizumab in pregnant women. Human IgG antibodies are known to cross the placenta, especially during the third trimester.” (source)

For breastfeeding, the same review notes that monoclonal antibodies can appear in breastmilk, but likely in very small amounts. Whether that’s enough to affect a baby is unknown.

My own experience echoes this: I’ve seen doctors decide against BIMZELX for pregnant women unless there’s no alternative, but it’s sometimes used during breastfeeding after a careful risk/benefit discussion.

Step 3: What Do the Experts Say? (With a Real Case Example)

At a recent dermatology meeting, Dr. Liu (a well-known clinical immunologist in Shanghai) shared her approach:

“If the mother’s disease is life-threatening or severely impairs quality of life, I sometimes continue anti-IL-17 therapy after carefully counseling about unknown risks. But for mild cases, I always recommend pausing treatment during pregnancy.”

In Anna’s case, after a long talk (and more than one phone call with her OB-GYN), she decided to postpone BIMZELX until after delivery. Her disease was bad, but not unmanageable with other treatments. Six months later, after stopping breastfeeding, she started BIMZELX with no problems.

Step 4: How Do Different Countries Handle This? (With Comparison Table)

Here’s where things get interesting. I’ve seen patients in China, the US, and Germany get different answers—and that’s not just down to the doctor, but the law and what counts as “verified safety.” Here’s a quick comparison:

Step 5: What If You’re Already Pregnant or Breastfeeding on BIMZELX?

Let’s say you find out you’re pregnant while on BIMZELX. This happened to a friend of mine—she panicked, stopped the drug immediately, and called both her dermatologist and her OB. The advice she got: don’t panic, but stop BIMZELX as soon as possible and monitor for any issues. No adverse outcomes occurred, and her baby was healthy. That’s consistent with what’s reported in the literature (source), but since the numbers are small, every case matters.

For breastfeeding, the same approach applies: discuss with your doctor, and if possible, wait until after breastfeeding to start or resume BIMZELX.

A Real-World Dispute: “Verified Trade” and Certification Analogy

Oddly enough, the confusion about BIMZELX reminds me of international trade standards. For instance, when A country exports “certified organic” apples to B country, each side checks different things: A might demand field inspections, B might only want paperwork. In the context of “verified” medical safety, the US FDA, EU EMA, and China’s NMPA all have different thresholds for what counts as “safe in pregnancy”—and patients fall into the cracks.

I once attended a WTO session on aligning pharmaceutical standards. The debate was heated: should we trust animal data, or only start recommending when large registry studies exist? In the end, the WTO’s technical barriers to trade agreement (source) basically says: every country can set its own rules, so long as they’re transparent. That’s exactly what’s happened with BIMZELX and pregnancy.

Summary & Next Steps: What Should You Actually Do?

Here’s what my experience and the evidence say:

• Avoid BIMZELX during pregnancy unless there are no alternatives and the benefits clearly outweigh the risks. The official recommendation in almost every country is to avoid it due to lack of data.
• For breastfeeding, consult closely with your doctor. It’s probably safer than during pregnancy, but the official line is still “caution.”
• If you become pregnant while taking BIMZELX, don’t panic but do notify your healthcare team right away and stop the drug as advised.
• Always check your country’s guidelines and have a frank discussion with both your dermatologist and your OB.
• Remember, “verified safety” can mean different things depending on where you are. When in doubt, err on the side of caution.

In my own practice, I always tell patients: “You know your body and your priorities best. I can give you the best data I have, but sometimes we’re working with incomplete information. Let’s make the decision together, and don’t be afraid to ask more questions.”

For more on how different countries set these standards, check the WTO’s Technical Barriers to Trade page and the OECD’s page on standards and certification.

Author: Dr. Alex Wang, MD, Dermatologist, with 10+ years’ clinical experience and a passion for demystifying complex drug safety issues. All quoted sources are from regulatory agencies or peer-reviewed journals, as linked above.