Starting a biologic therapy for inflammatory bowel disease (IBD) can feel unfamiliar, especially if you have not had intravenous (IV) treatment or self-injected medication before. Knowing what happens during the appointment, how your body may respond, and what to watch for afterwards can reduce uncertainty and help you feel more prepared.
What Are Biologic Therapies?
Biologics are medicines made from living cells that target specific parts of the immune system involved in driving inflammation in Crohn’s disease and ulcerative colitis. Unlike conventional drugs that affect the whole body in broader ways, biologics block individual proteins or immune signals, such as tumour necrosis factor alpha (TNF-α), interleukin-12, interleukin-23, or integrin molecules that allow immune cells to enter gut tissue. By interrupting these pathways, biologics reduce inflammation in the intestines and help achieve or maintain remission.
Most biologics used in IBD are given either as an infusion into a vein or as an injection under the skin, depending on which biologic your gastroenterologist has prescribed.
Infusions: What Happens in the Clinic
If your biologic is delivered by infusion, you will attend a hospital or clinic infusion suite, typically a quiet room with comfortable chairs or beds.
Before You Arrive
You may be asked to confirm you are well on the day of the infusion. If you have an active infection, high fever, or feel particularly unwell, contact the IBD team before attending. Some centres check your temperature, blood pressure, and pulse before starting.
During the Infusion
A nurse will insert a small plastic tube called a cannula into a vein, usually in your arm or hand. The biologic is delivered slowly over a set period, which varies by drug. Infliximab typically takes around two hours, while vedolizumab may take 30 minutes to an hour.
You will be monitored throughout. Most people read, listen to music, or rest. You can usually eat, drink, and use the toilet during the infusion. The medical team will check for signs of an infusion reaction, which can include flushing, itching, tight chest, or headache. Reactions are uncommon and usually mild. If one occurs, the infusion can be paused or slowed, and medication such as an antihistamine or paracetamol can be given.
After the Infusion
Once complete, you will be observed for a short time, often 30 minutes to an hour, before leaving. Most people can drive themselves home and return to normal activities the same day, though some may feel tired.
Injections: At Home or in Clinic
Some biologics are given as a subcutaneous injection, meaning the medicine is delivered under the skin. These include adalimumab, golimumab, ustekinumab, and some biosimilar versions.
First Injection
Your first injection may be given in a clinic or at home. If at home, an IBD nurse will usually visit to demonstrate the technique and supervise the first dose. You will be shown how to prepare the injection, choose an injection site (usually the front of the thigh or lower abdomen), and dispose of the needle safely.
Some injections come as a pre-filled pen, others as a pre-filled syringe. The medication is stored in the fridge and should be taken out around 30 minutes before use so it reaches room temperature, making the injection more comfortable.
What It Feels Like
The needle is small and thin. The sensation is brief, similar to a small pinch or bee sting. Some people notice mild stinging as the liquid enters the tissue, usually lasting a few seconds.
After the injection, you may see a small red mark or slight bruising at the site. This is normal and fades within a day or two. Rotating injection sites with each dose helps reduce irritation.
Ongoing Injections
Once confident, most people self-inject at home. Some biologics are given weekly, others every two weeks or monthly. You will be provided with clear instructions, sharps bins for safe disposal, and contact details for your IBD nurse.
What to Expect in the First Few Weeks
Biologic therapies do not work immediately. It can take several weeks, sometimes a few months, to notice a reduction in symptoms. This delay occurs because biologics work by gradually dampening overactive immune responses rather than providing instant symptom relief.
During the initial weeks, you may continue to experience diarrhoea, urgency, abdominal discomfort, or fatigue. This does not mean the biologic is not working. The medication is beginning to influence the immune pathways driving inflammation, but visible clinical improvement takes time.
Some people feel an improvement in energy or slight easing of symptoms within the first two to four weeks. Others notice little change until after the second or third dose. Your gastroenterologist will usually assess response after 12 to 16 weeks and may adjust treatment if needed.
Possible Side Effects
Most people tolerate biologics well, but side effects can occur.
Infusion or Injection Site Reactions
These are most common. For infusions, mild reactions such as flushing, headache, or nausea may occur during or shortly after treatment. For injections, redness, swelling, or tenderness at the injection site is common and usually resolves quickly.
Infections
Because biologics reduce immune activity, there is a slightly increased risk of infections. Common infections such as colds, sore throats, or urinary tract infections may occur more frequently or take longer to clear. Serious infections are uncommon but possible. Contact your IBD team promptly if you develop a fever, persistent cough, unusual fatigue, or other signs of infection.
This is also why your team will screen you before you start. Tests for tuberculosis and hepatitis B are standard before beginning a biologic, because these infections can reactivate once the immune system is suppressed. Your vaccination history will usually be reviewed at the same time.
Severe Allergic Reactions
Rarely, a biologic can cause a severe allergic reaction (anaphylaxis), usually during or shortly after an infusion. This is why infusions are given in a clinical setting with staff and equipment on hand, and why you are observed afterwards. Tell the nursing team immediately if you develop difficulty breathing, swelling of the face, lips or throat, chest tightness, a widespread rash, or feel faint during treatment. If any of these develop after you have gone home, or after a self-administered injection, call 999 or go to A&E rather than waiting to contact your IBD team.
Delayed Hypersensitivity
Some people develop delayed reactions, such as joint pain, rash, or flu-like symptoms, several days after the first few doses. These are uncommon and usually resolve with continued treatment or a switch to a different biologic.
What You Can Do to Prepare
There is no need to fast before an infusion or injection unless instructed otherwise. Staying hydrated, eating normally, and dressing comfortably can help the appointment go smoothly.
If you feel anxious, let the nursing team know. They are experienced in supporting first-time biologic patients and can explain each step as it happens. Bringing something to occupy yourself during an infusion can help the time pass.
Monitoring and Follow-Up
Your IBD team will arrange blood tests and clinical reviews at regular intervals to monitor how well the biologic is working, check for side effects, and measure drug levels in your blood. These tests help ensure the dose is right for you and that your body is responding as expected.
You will be asked to report any new symptoms, infections, or changes in your health. Open communication with your IBD team is important for managing treatment safely and effectively.
Practical Takeaways
- Allow time for your appointment. Infusions can take two to three hours including observation. Injections are quicker but may take longer the first time.
- Bring something to do if attending for an infusion. Comfort and distraction can make the experience easier.
- Report any signs of infection promptly. This includes fever, persistent cough, or unusual tiredness.
- Be patient with symptom improvement. Biologics take weeks to months to reach full effect.
- Rotate injection sites if self-injecting. This reduces irritation and makes each injection more comfortable.
- Keep your IBD team informed. Tell them about side effects, missed doses, or any concerns.
Conclusion
Starting a biologic for IBD is a significant step in managing inflammation and working towards remission. Whether you are attending for an infusion or learning to self-inject, the process becomes routine with time. Most people tolerate biologics well and benefit from their targeted approach to reducing immune-driven inflammation. Staying in close contact with your IBD team and reporting any concerns early will help ensure the treatment is both safe and effective.
References
- Feagan BG, Rutgeerts P, Sands BE, et al. Vedolizumab as induction and maintenance therapy for ulcerative colitis. N Engl J Med. 2013;369(8):699-710. doi:10.1056/NEJMoa1215734
- Colombel JF, Sandborn WJ, Reinisch W, et al. Infliximab, azathioprine, or combination therapy for Crohn’s disease. N Engl J Med. 2010;362(15):1383-1395. doi:10.1056/NEJMoa0904492
- Sandborn WJ, Feagan BG, Marano C, et al. Subcutaneous golimumab induces clinical response and remission in patients with moderate-to-severe ulcerative colitis. Gastroenterology. 2014;146(1):85-95. doi:10.1053/j.gastro.2013.05.048
- Hanauer SB, Feagan BG, Lichtenstein GR, et al. Maintenance infliximab for Crohn’s disease: the ACCENT I randomised trial. Lancet. 2002;359(9317):1541-1549. doi:10.1016/S0140-6736(02)08512-4
- Sands BE, Feagan BG, Rutgeerts P, et al. Effects of vedolizumab induction therapy for patients with Crohn’s disease in whom tumor necrosis factor antagonist treatment failed. Gastroenterology. 2014;147(3):618-627. doi:10.1053/j.gastro.2014.05.008
- Vermeire S, D’Haens G, Baert F, et al. Efficacy and safety of subcutaneous vedolizumab in patients with moderately to severely active Crohn’s disease: results from the VISIBLE 1 trial. J Crohns Colitis. 2022;16(1):27-38. doi:10.1093/ecco-jcc/jjab127
- Panaccione R, Ghosh S, Middleton S, et al. Combination therapy with infliximab and azathioprine is superior to monotherapy with either agent in ulcerative colitis. Gastroenterology. 2014;146(2):392-400. doi:10.1053/j.gastro.2013.10.052
- Sandborn WJ, Rutgeerts P, Gasink C, et al. Long-term efficacy and safety of ustekinumab for Crohn’s disease through the second year of therapy. Aliment Pharmacol Ther. 2018;48(1):65-77. doi:10.1111/apt.14794
This article is intended for informational and educational purposes only. It does not constitute medical advice and should not be used as a substitute for professional medical guidance, diagnosis, or treatment.