Biologics for Crohn’s: Infusion vs Injection + What a “Loading Schedule” Means
Last Updated Jan 15, 2026
Biologics for Crohn’s disease are targeted medicines that calm down parts of the immune system that drive gut inflammation. They are often used for moderate to severe disease, especially when other treatments have not controlled symptoms or inflammation. Some biologics are given by intravenous (IV) infusion in a clinic, while others are given by subcutaneous (under-the-skin) injection at home, and a few use a mix of both. Understanding the delivery method and the early “loading schedule” (also called induction dosing) can make treatment decisions feel less overwhelming and help set realistic expectations for how the first few months may look.
Infusion vs injection: what’s different and why it matters
Infusions happen in an infusion center or clinic. The medication goes into a vein, usually over a set time, and the visit may include monitoring before and after. Infusions are common for certain anti-tumor necrosis factor (anti-TNF) options used in Crohn’s (such as infliximab), while other anti-TNF Crohn’s options are designed for at-home injections (such as adalimumab and certolizumab). [1]
Injections are typically taught in the clinic first, then continued at home on a schedule. This can mean more independence and less time in a medical setting, but it also adds responsibilities like medication storage, remembering dose days, and comfort with self-injection (or help from a caregiver). Some treatments commonly discussed in Crohn’s care include vedolizumab Crohn’s and ustekinumab Crohn’s, and depending on the specific product and plan, these may involve IV doses, injections, or an IV start followed by injections. [2]
A few practical infusion day tips that many people find helpful include:
- Wearing loose sleeves for IV access and comfortable layers
- Bringing headphones, a charger, and something to do
- Packing water and a snack (if allowed by the site)
- Writing down any symptoms that happened after the last dose to share with the team
What a “loading schedule” means, common side effects, and tracking response
A loading schedule (also called induction dosing) means the first doses are given closer together, or at a higher amount, to help the medication reach an effective level in the body sooner. After induction, most people move to maintenance dosing, which is the longer-term schedule. Examples of induction patterns seen with biologics for Crohn’s include IV doses at weeks 0, 2, and 6 for some infusion therapies, higher starter doses for some injection therapies, or one IV starter dose followed by injections every several weeks. [2]
Side effects vary by drug, but common themes across biologics include injection-site reactions (redness, itching, soreness), upper respiratory infections, fatigue, and headache. Some infusion medications can also cause an allergic reaction during or after an infusion (for example rash, itching, swelling, or trouble breathing), which is one reason monitoring is part of infusion visits. [3] Because biologics can affect immune responses, clinicians often screen for infections like tuberculosis (TB) and hepatitis B before starting certain therapies. [4] Vaccine planning also matters, since live vaccines are generally not recommended for people with inflammatory bowel disease (IBD) who are taking immune-suppressing medicines. [5]
Tracking response usually includes both how someone feels and what tests show. Many care teams aim for symptom improvement plus better inflammation markers and, over time, signs of healing on imaging or endoscopy (a treat-to-target approach). [6] A simple way to support this is keeping notes on stool frequency, abdominal pain, fatigue, weight changes, fevers, and dose dates, then pairing that with scheduled labs or stool tests recommended by the gastroenterology team.