What is certolizumab?
Certolizumab pegol (brand name Cimzia) is a biologic medication used to treat rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, axial spondyloarthritis, and Crohn’s disease. It belongs to the TNF inhibitor class but has a unique structure that sets it apart — particularly when it comes to pregnancy safety.
How it works
Certolizumab is a TNF inhibitor. It targets tumor necrosis factor-alpha (TNF-alpha), a protein your immune system overproduces in autoimmune conditions. Excess TNF-alpha drives the inflammation that causes joint pain, swelling, stiffness, and tissue damage.
What makes certolizumab unique is its structure. It is a PEGylated Fab’ fragment of an anti-TNF antibody. In plain terms: it’s only the “business end” of the antibody — the part that grabs TNF — attached to a polyethylene glycol (PEG) molecule that helps it last longer in your body. It lacks the Fc portion that other antibody-based biologics have. This distinction matters most for pregnancy (see below).
How to take it
- Loading dose: 400 mg (given as two 200 mg injections) at weeks 0, 2, and 4
- Maintenance dose: 200 mg every 2 weeks or 400 mg every 4 weeks (your doctor will determine which schedule is right for you)
- Cimzia is available in two forms:
- Prefilled syringe for self-injection at home — the most common option
- Lyophilized (powder) vial that is reconstituted and injected in the office — most useful for patients who cannot self-inject or in specific insurance situations (such as Medicare Part B, which covers in-office administration)
- Store in the refrigerator — remove and let it warm to room temperature for approximately 30 minutes before injecting
- Rotate injection sites between the thigh and abdomen (at least 2 inches from the navel)
What to expect when starting
The loading dose schedule helps build the medication to effective levels faster. Many patients begin to notice improvement within 2–4 weeks, with the full effect typically reached by 3 months.
Your doctor may recommend combining certolizumab with methotrexate for rheumatoid arthritis, as the combination can improve effectiveness and reduce the chance of developing antibodies to the drug.
Why certolizumab stands out for pregnancy
Because certolizumab lacks the Fc region, it does not actively cross the placenta the way other antibody-based TNF inhibitors do. Studies have confirmed minimal to no drug transfer to the infant. This makes certolizumab the preferred TNF inhibitor for women who are pregnant or planning pregnancy.
If you are a woman of childbearing age and need a TNF inhibitor, certolizumab is often the first choice. Discuss family planning with your rheumatologist — we can help you time your treatment for the safest outcome.
Side effects to watch for
Common:
- Injection site reactions — redness, itching, or swelling at the injection site. These are usually mild and improve over time.
Important — contact us if you experience:
- Fever, chills, or any signs of infection (sore throat, cough, burning with urination, a wound that isn’t healing)
- Unusual fatigue or feeling persistently unwell
- New numbness, tingling, or vision changes (very rare neurological side effect)
- New or worsening heart failure symptoms (shortness of breath, leg swelling)
Important: Like all TNF inhibitors, certolizumab reduces part of your immune defense. Take infections seriously and contact us early rather than waiting it out.
Required screening before starting
Before your first dose, we will check:
- TB screening (QuantiFERON blood test or PPD skin test) — TNF inhibitors can reactivate latent tuberculosis
- Hepatitis B screening — TNF inhibitors can reactivate dormant hepatitis B infection
- Baseline blood work including CBC and metabolic panel
- Review of your vaccination history — certain vaccines should be given before starting
Things to avoid
- Live vaccines — including live shingles vaccine (Zostavax), live nasal flu spray, and MMR. Inactivated vaccines (flu shot, COVID, Shingrix) are safe and recommended. Talk to us before any vaccination.
- Other biologics — certolizumab should not be taken with another biologic medication. Combining biologics significantly increases infection risk without added benefit.
- Don’t ignore infections — contact us if you develop fever, chills, or any signs of infection. We may advise holding a dose until the infection clears.
Frequently asked questions
Why does my doctor recommend certolizumab over other TNF inhibitors? There are several reasons your doctor may choose certolizumab. If you are a woman of childbearing age or planning pregnancy, it has the strongest safety data for use during pregnancy. It may also be chosen based on your specific condition, insurance coverage, or dosing preference.
What’s the difference between every-2-week and every-4-week dosing? Both schedules deliver the same total amount of medication over time. Your doctor will choose the schedule that best fits your condition and lifestyle. Some patients prefer the convenience of monthly dosing.
What if I miss a dose? Take it as soon as you remember, then resume your regular schedule. Do not double up on doses. If you’re unsure, call our office.
Can I take certolizumab while breastfeeding? Certolizumab has very low transfer into breast milk due to its unique structure. Current evidence suggests it is compatible with breastfeeding, but discuss this with your rheumatologist.
Are there rare but serious risks I should know about? Like all TNF inhibitors, certolizumab carries rare risks including reactivation of latent TB or hepatitis B (which is why we screen), very rare cases of demyelinating disease, and a theoretical small increase in lymphoma risk — though the background lymphoma rate is already elevated in patients with active inflammatory disease. These risks are rare, and for most patients the benefits of disease control far outweigh them.
This handout is for informational purposes and does not replace the advice of your physician. Always follow the specific instructions given to you by your rheumatologist. If you have questions or concerns about your medication, contact Synergy Rheumatology & Wellness.