Treatment of Active Crohn's Disease
For adults with moderate-to-severe active Crohn's disease, TNF antagonists (infliximab or adalimumab) should be initiated as first-line advanced therapy, with consideration for combination therapy with a thiopurine for infliximab specifically. 1
Induction Therapy
First-Line Advanced Therapy Options
The 2025 AGA guidelines establish TNF antagonists as the cornerstone of treatment for moderate-to-severe Crohn's disease 1. The evidence supports:
- TNF antagonists (infliximab, adalimumab) as preferred initial advanced therapy
- IL-23 inhibitors (risankizumab, mirikizumab, guselkumab) as effective alternatives
- Ustekinumab (IL-12/23 inhibitor) as another first-line option
- Vedolizumab for gut-selective therapy
The British Society of Gastroenterology 2025 guidelines note that adalimumab and ustekinumab demonstrate equal efficacy in biologic-naïve patients 2, providing flexibility in initial drug selection.
Combination vs. Monotherapy
For infliximab specifically, combination therapy with a thiopurine (azathioprine or 6-mercaptopurine) is recommended 1. However, the European guidelines recommend adalimumab as monotherapy rather than in combination 1. This distinction is critical—infliximab benefits from immunomodulator co-therapy to reduce immunogenicity, while adalimumab does not show the same advantage.
Role of Corticosteroids
Corticosteroids remain effective for inducing remission but should never be used for maintenance therapy 2. When used:
- Prednisolone or methylprednisolone at 60 mg daily equivalent 3
- Treatment duration of 8-16 weeks 4, 5
- Budesonide 9 mg daily is preferred for mild-to-moderate disease due to fewer systemic side effects 6
A critical pitfall: corticosteroids achieve remission in 60-83% of patients but do not maintain it 6. Patients requiring corticosteroids should transition to advanced therapy or immunomodulators for maintenance.
Obsolete or Limited Therapies
Mesalamine/5-ASA should not be used for Crohn's disease 6. The evidence shows it is "clinically no more effective than placebo" for small bowel disease 6. This represents a major shift from historical practice.
Maintenance Therapy
After Successful Induction
Continue the agent that successfully induced remission 2. Specific maintenance strategies:
- TNF antagonists: Continue at standard maintenance intervals
- Thiopurines: Can be used for maintenance, though they require induction with another agent first 2
- Methotrexate: Parenteral administration for both induction and maintenance 1
Combination Therapy Withdrawal
For patients on infliximab plus thiopurine who achieve stable remission for >6 months, consider withdrawing the thiopurine after 6-12 months 1, 2. This reduces long-term immunosuppression risks while maintaining efficacy with biologic monotherapy.
Treatment Sequencing After First Advanced Therapy Failure
The 2025 AGA guidelines conditionally recommend risankizumab over ustekinumab in patients with prior TNF antagonist exposure 1. This represents the most recent evidence on drug positioning.
Upadacitinib (JAK inhibitor) recommendations vary by guideline:
- American College of Gastroenterology: Use only after TNF antagonist exposure 1
- British Society and European guidelines: Can be used regardless of prior exposure 1
Given the divergence, the safer approach is to reserve upadacitinib for TNF-experienced patients, particularly given its side effect profile requiring careful patient selection.
Treatment Strategy: Top-Down vs. Step-Up
Upfront use of advanced therapy (top-down approach) is conditionally recommended over traditional step-up therapy 1. The rationale:
- Prevents long-term complications
- Achieves better mucosal healing
- Reduces need for surgery
- Avoids prolonged corticosteroid exposure
However, for truly mild disease, observation without treatment remains an option for select patients with minimal symptoms 6.
Treatment Targets
Mucosal healing is the recommended treatment target, not just symptom control 1. This requires:
- Biochemical monitoring (CRP, fecal calprotectin)
- Endoscopic assessment when indicated 3
- Treat-to-target monitoring every 26-52 weeks 7
Special Considerations
Intestinal Obstruction
Intravenous corticosteroids should be used when there is evidence of active inflammation 3. Surgical consultation is essential as obstruction may represent fibrotic stricture requiring intervention.
Intra-abdominal Abscess
Treatment requires infection control with drainage (depending on size/location) plus systemic antibiotics 3. Medical therapy decisions follow abscess resolution.
Perianal Disease
Requires multidisciplinary approach with both medical and surgical management 3. TNF antagonists (infliximab or adalimumab) are first-line for complex perianal fistulas 7.
Critical Pitfalls to Avoid
- Never use corticosteroids for maintenance—they do not prevent relapse and cause significant long-term toxicity
- Do not use mesalamine for Crohn's disease—it lacks efficacy despite historical use
- Do not delay advanced therapy in moderate-to-severe disease—early intervention prevents complications
- Do not forget VTE prophylaxis—hospitalized IBD patients require anticoagulation 3
- Do not use thiopurines alone for induction—they require 3-4 months to work and need combination with faster-acting agents 2