Yes, you can switch from one Crohn's biologic to another. This may be an option when your current medicine does not work, stops working over time, or causes difficult side effects. Your gastroenterologist may recommend another medicine in the same drug class or one that works differently. The best choice depends on why the switch is needed, your disease activity, your treatment history, and your overall health.
Why might you need to switch Crohn's biologics?
Biologics are medicines that target specific parts of the immune system involved in inflammation. They can help control Crohn's disease, reduce symptoms, and maintain remission. However, the same medicine does not work equally well for everyone, and a treatment that works initially may become less effective over time.
According to Crohn's & Colitis UK, a change in treatment may be considered when a biologic does not work well enough, loses its effect, or causes side effects that are serious or difficult to manage. Switching is a recognized part of long-term Crohn's disease management, rather than an indication that no treatments remain available.
1. Your first biologic does not work well enough
Some people do not experience enough improvement after starting a biologic. Doctors may describe this as primary non-response when the medicine does not produce the expected initial benefit. If symptoms and evidence of inflammation remain despite an adequate treatment course, your gastroenterologist may consider a different biologic or another targeted medicine.
Before changing treatment, the doctor will consider whether the medicine has had enough time to work and whether active Crohn's inflammation is actually responsible for your ongoing symptoms. This helps distinguish a treatment that has not worked from symptoms caused by another problem.
2. Your biologic worked at first but has stopped working
A medicine may control Crohn's disease for months or years and then become less effective. This is known as secondary loss of response. One possible reason is that the body develops antibodies against the biologic, which can interfere with how well the medicine works. Low levels of the medicine in the bloodstream may also contribute to treatment failure.
Depending on the findings, your doctor might adjust the dose, shorten the time between doses, or recommend switching medicines. In some situations, another biologic from the same class may work well. In others, choosing a drug with a different mechanism of action may be more appropriate.
3. You experience side effects
Side effects can also lead to a change in biologic treatment. The right response depends on the type of reaction, its severity, and the risks of continuing the medicine. Some problems may be manageable, while others may mean that a different treatment is safer or better suited to your circumstances.
Contact your healthcare team if you develop new or concerning symptoms while taking a biologic. A suspected serious reaction needs prompt medical assessment. Do not stop, restart, or change your dose without discussing the plan with your treating team, unless you have been given specific emergency instructions.
What types of Crohn's biologics can you switch between?
Crohn's biologics belong to different drug classes. Each class targets a particular part of the immune response that contributes to inflammation. Your doctor may recommend changing to another medicine in the same class or selecting one that acts on a different target.
The Crohn's & Colitis Foundation describes several biologic treatment options for inflammatory bowel disease. Examples used in Crohn's disease include:
- Anti-TNF medicines: Infliximab and adalimumab block tumor necrosis factor (TNF), a protein involved in inflammation.
- Integrin inhibitors: Vedolizumab targets a pathway involved in moving certain immune cells into the gut.
- IL-12/23 inhibitors: Ustekinumab targets proteins involved in immune signaling and inflammation.
- IL-23 inhibitors: Medicines such as risankizumab target a protein involved in inflammatory signaling.
These examples are not an exhaustive list, and not every option is suitable for every patient. Availability, approved uses, and eligibility can vary by country and age group. Some targeted treatments for Crohn's disease are not biologics, even though they may be considered when a biologic has not worked.
Is it better to switch within the same class or to a different class?
There is no single answer for everyone. The most useful approach depends partly on whether the current medicine never worked, gradually lost effectiveness, or caused side effects.
Switching to another biologic in the same class
A within-class switch means changing to a medicine that acts on the same general target. For example, a person taking one anti-TNF medicine might switch to another anti-TNF medicine. This may be considered when the first medicine initially worked but later became less effective, particularly when the treatment history and test results suggest that another medicine in that class could still help.
However, changing within the same class does not guarantee a better response. If the first medicine did not help despite adequate drug exposure, your gastroenterologist may consider whether a different mechanism is more appropriate.
Switching to a biologic with a different mechanism
An out-of-class switch involves moving to a medicine that targets a different inflammatory pathway. For example, someone who has not responded adequately to an anti-TNF medicine may be considered for a biologic that acts on another target. The choice depends on previous treatment responses, the pattern of Crohn's disease, other medical conditions, safety considerations, and the options available.
The American Gastroenterological Association provides evidence-based guidance on choosing treatments for moderate-to-severe Crohn's disease, including options relevant to people who have received previous therapy. This supports an individualized approach: the next medicine should be selected according to the person's treatment history and clinical needs, rather than simply choosing the next available drug.
What tests might your doctor recommend before switching?
Before deciding that a biologic has failed, your gastroenterologist may review your symptoms, treatment schedule, examination findings, and evidence of intestinal inflammation. Ongoing diarrhoea, abdominal pain, fatigue, or other symptoms do not always mean that Crohn's inflammation is active. Infection and other conditions may produce similar symptoms and sometimes need different treatment.
Depending on your situation, the assessment may include:
- Blood tests: Tests such as C-reactive protein (CRP) can help assess inflammation. Other blood tests may be used to check for anaemia or other concerns.
- Stool tests: Faecal calprotectin can help assess inflammation in the intestines. Stool testing may also be used to investigate infection when appropriate.
- Drug-level and antibody testing: For selected anti-TNF treatments, measuring the medicine level and checking for antibodies against it may help explain a reduced response.
- Endoscopy or imaging: These investigations may be recommended when doctors need a clearer picture of inflammation or Crohn's-related complications.
The European Crohn's and Colitis Organisation (ECCO) discusses therapeutic drug monitoring and the use of objective measures of inflammation in Crohn's disease management. Such testing may help guide decisions, but not every patient needs every investigation. The appropriate assessment depends on the medicine being used and the clinical circumstances.
How is the switch from one biologic to another planned?
Once you and your gastroenterologist have chosen a new treatment, the next step is to plan the transition. The schedule depends on the medicines involved, the reason for switching, the timing of the last dose, and any safety concerns. There is no single switching schedule that applies to every biologic.
Will you need a break between the two medicines?
Some switches can be arranged around the next scheduled treatment dose, while others may involve a gap between medicines. A break between treatments is sometimes called a washout period. It may be considered to address safety concerns, but a washout is not automatically necessary for every patient, and the evidence supporting routine breaks varies by situation.
Your healthcare team will weigh the risks of infection and other complications against the risk of leaving Crohn's disease insufficiently controlled. Do not create your own treatment gap or take both biologics together unless your clinician has specifically instructed you to do so.
What checks are needed before starting the new biologic?
Your team may review your medical history, previous reactions to treatment, current medicines, infection risks, and vaccination status. Blood tests or infection screening may be appropriate depending on the medicine you are starting and your individual circumstances. You should also confirm how the new treatment is given, when the first dose is due, and whom to contact if symptoms worsen or a dose is delayed.
If the new treatment is an injection or infusion, the administration process may differ from your previous medicine. Make sure you understand the new schedule and any monitoring appointments before the transition begins.
How long does it take to know whether the new biologic is working?
The time needed to assess a new biologic varies by medicine and by person. Some improvement may occur before the full treatment effect can be judged. Your care team will explain when to expect an initial response and when it will be appropriate to review whether the treatment is meeting its goals.
Monitoring usually considers more than how you feel. Your doctor may assess changes in bowel symptoms, energy levels, and daily functioning alongside blood or stool markers of inflammation. Endoscopy or imaging may also be used when needed. This helps determine whether the new medicine is controlling inflammation, even when symptoms alone do not provide a complete picture.
If the new biologic does not achieve the agreed treatment goals, your gastroenterologist can reassess the results and discuss the next step. That may involve optimizing treatment, investigating another cause of symptoms, or considering a further change in medication.
Does switching to a biosimilar count as changing biologics?
Switching to a biosimilar is different from switching to a biologic with a different active medicine. A biosimilar is highly similar to an already approved biologic, with no clinically meaningful differences in safety or effectiveness expected for its approved use. A switch may occur because of cost, supply, insurance coverage, or local prescribing arrangements.
According to the Crohn's & Colitis Foundation's information on biosimilars, evidence supports switching from an originator biologic to its biosimilar without an expected increase in loss of response or side effects. A biosimilar switch is therefore not the same as moving to a new drug class because Crohn's disease is not responding to treatment.
Even when the active medicine is highly similar, you may notice differences in the injection device, packaging, or delivery arrangements. Confirm the exact product you have been prescribed and ask your healthcare team for instructions if the device or administration process has changed.
What should you discuss with your gastroenterologist?
A useful conversation focuses on why the current treatment is being changed and what the new medicine is expected to achieve. You may want to ask:
- Is there evidence that my Crohn's disease is still active, or could something else explain my symptoms?
- Could adjusting the current dose or schedule be helpful before changing medicines?
- Why is the proposed biologic a better option for me, and how does it differ from my current treatment?
- When should I stop the old medicine and start the new one?
- What side effects, infection symptoms, or other problems should I report?
- Which tests will show whether the new treatment is working, and when will we review the results?
If symptoms are persistent, worsening, or disrupting daily life, contact your IBD team rather than waiting for the next routine appointment. Severe abdominal pain, heavy rectal bleeding, persistent vomiting, or signs of significant dehydration warrant urgent medical assessment.
Can you switch biologics more than once?
Yes. Some people need to try more than one biologic over the course of Crohn's disease management. A previous unsuccessful treatment does not automatically mean that another biologic will fail, because different medicines act on different inflammatory pathways and treatment responses can vary.
Each additional switch should be based on a review of previous treatments, the reasons they were stopped, the current evidence of inflammation, and the benefits and risks of available options. The aim is to find a treatment that controls disease activity, supports day-to-day functioning, and can be continued safely over time.