What Happens During Immunotherapy?

When people hear “immunotherapy,” it can sound intimidating — almost sci-fi. In reality, it’s a form of treatment that helps your own immune system recognize and attack cancer cells more effectively. Rather than targeting the tumor directly with chemicals or radiation, immunotherapy helps your body’s defense system do the heavy lifting.

At Cancer Care Institute, Dr. Youram Nassir and our team use immunotherapy thoughtfully as part of individualized care plans. Many patients are curious not just about why they’re getting it, but what actually happens during treatment — especially emotionally and physically. Here’s a breakdown of what to expect.

Understanding your plan before treatment

Before your first infusion or dose, you meet with your care team to review your diagnosis, treatment goals, and expected timeline. This includes talking about:

• The specific immunotherapy agent you’ll receive
• How often you’ll be treated
• Possible side effects and how we monitor them
• Which labs and scans are scheduled to track progress

You’ll likely have bloodwork before your first session so your team can establish a baseline and customize supportive care.

This preparation helps us avoid surprises and gives you a clear roadmap of what comes next.

What happens during an immunotherapy session

Immunotherapy is usually given through an intravenous (IV) infusion, similar to receiving fluids or medications. However, some newer treatments may be given as injections or oral therapies, depending on the drug.

When you arrive for your session, here’s what a typical visit feels like:

1. A warm welcome and check-in

Our nurses, who know your history and treatment plan, greet you and get you settled. Then, they check your vital signs, review any new symptoms, and answer your questions. We believe this personal connection is one of the most reassuring parts of the experience.

2. IV access and setup

We place a small needle, or catheter, in your arm or hand to deliver the medication. If you’re sensitive to needles, don’t worry; we go slow, talk you through it, and make you as comfortable as possible.

3. The infusion itself

Immunotherapy infusions can take anywhere from about 30 minutes to several hours, depending on the specific medication, dose, and how your body responds. During your appointment, you’ll relax in our comfortable treatment room while a trained medical professional closely monitors you throughout the infusion. Many patients use this time to read, watch TV, listen to music or podcasts, or chat quietly with other patients. You’re welcome to bring personal items like a blanket, headphones, a book, or even a small snack (if approved by your care team) to help you feel more at ease. Most people describe infusion time as calm and low-stress—almost like a quiet break in the middle of a busy day, with attentive care always nearby.

4. Side effect monitoring

Your team watches for reactions during and after the infusion. Some immune-related side effects can arise hours or days later, making communication important.

Unlike some traditional chemotherapy, immunotherapy doesn't always hit every cell in your body. That’s one reason side effects of immunotherapy can feel different and why the experience isn’t always as exhausting.

What immunotherapy feels like 

Experiences vary from person to person, but patients report common themes:

Subtle energy changes

Some people feel more tired on treatment days and the day after, while others feel normal or even energized. Fueling yourself with good food and hydration makes a big difference.

Physical sensations

During infusion, most people feel nothing more than the fluids entering their vein. Occasionally, you may feel warmth, flushing, chills, mild itching, or a sense of pressure. We monitor you closely for any concerning signs.

Delayed effects

Unlike traditional chemotherapy symptoms that hit quickly, some immunotherapy side effects can show up later. These can include rash, mild joint aches, or low-grade fever. That’s intentional; it’s your immune system activating. But it’s also why we provide patients with clear guidance on when to call their care team.

What to expect after the infusion

Once your session is over, you’ll stay a short while so nurses can make sure you’re stable. Most patients walk out and return to their day with minimal downtime. In the hours and days that follow, tracking how you feel becomes part of the process.

Many of our patients say things like:

• “I felt okay during treatment, but tired later.”
• “I got a bit of a headache the next day.”
• “My appetite changed temporarily.”

These are common and manageable with support. Our team will help you separate normal changes from symptoms needing attention.

Our treatment plan includes returning the next day for a hydration session to help support your body and reduce potential side effects from the treatment. This additional hydration helps replenish fluids, supports kidney function, and can ease symptoms such as fatigue or headaches. The session is typically brief and well tolerated, and many patients find it helps them feel better and recover more comfortably after treatment.

Progress isn’t always a straight line

One of the unique aspects of immunotherapy is that results can evolve over time. Some patients see tumor shrinkage quickly; others notice gradual changes. 

In some cases, the immune response looks like progression before it looks like improvement — a pattern called pseudoprogression. Your care team knows how to interpret scans and symptoms so you aren’t left guessing.

Regular imaging, labs, and symptom checks help us adjust your plan as needed.

To learn more or schedule a consultation, call Cancer Care Institute in Los Angeles, or request an appointment online today. You don’t have to go through this alone. We’re here with you.