What to Eat and Drink Before an Immunotherapy Session — You Don't Need to Fast

No. A routine immunotherapy infusion does not require fasting. Eat and drink normally before you come. The pre-cycle blood tests taken on the day — blood counts, liver, kidney and thyroid tests — do not need an empty stomach either. This is the answer most people are looking for, and it is genuinely reassuring.

The confusion is understandable. Many hospital appointments do require fasting, so patients assume every cancer treatment does. Immunotherapy is not one of them. It is an intravenous drip given while you sit awake in a chair, with no anaesthesia and no sedation, so there is no airway reason to keep your stomach empty.

The exceptions are real, and they are worth checking. Fasting is asked for when something else is booked on the same day. A PET-CT usually needs several hours without food and without sugary drinks. A contrast CT may have its own instruction. A sedated procedure, a biopsy or an endoscopy will. So will a specific fasting sugar or fasting lipid test if your doctor has ordered one. In every case the fasting comes from that test, not from the immunotherapy.

Response-assessment PET-CT is coordinated at partner imaging centres rather than done at the day-care unit, so a scan day is usually a separate appointment with its own preparation sheet. Read your own appointment slip the night before. If any line on it is unclear, ring the day-care unit and ask — it takes two minutes and saves a wasted trip.

One caution in the other direction: do not fast on your own initiative either. Skipping breakfast to "keep the body clean" before a drip makes a long morning harder, and it is genuinely unsafe if you take diabetes medication.

General guidance for a routine day-care visit, in line with ASCO and NCCN patient-education advice on eating and food safety during cancer treatment. Visit length varies with blood-test and pharmacy turnaround, so no centre can promise a fixed wait. If you have diabetes, kidney or heart disease, or a fluid restriction, your own doctor's instruction overrides this table.

1. 1

   Check the night before whether anything else is booked that day

   Read your appointment slip and ask the day-care unit whether a scan, a contrast study or a sedated procedure is booked on the same day. Those tests, not the drip, are what create fasting instructions.

2. 2

   Eat and drink normally the evening before

   Have your usual home dinner rather than a heavy oily or spicy meal. Drink water through the evening. Skip alcohol the night before, because it dehydrates you and can affect the liver blood tests taken at the visit.

3. 3

   Eat a light breakfast on the morning of the infusion

   Eat something familiar, warm and easy on the stomach two to three hours before you leave. Idli, upma, dosa, curd rice, khichdi, dal and rice, roti with dal, poha or bread with egg all work. Do not skip breakfast.

4. 4

   Drink water before you leave home

   Drink two to three glasses of water in the two hours before you leave, unless your doctor has restricted your fluids. Being well hydrated makes veins easier to find and cannulation easier.

5. 5

   Carry your own food and water to the day-care unit

   A routine cycle usually keeps you at the unit for several hours, and the timing varies with lab and pharmacy turnaround. Carry home-cooked food in a clean box, a filled water bottle, and any medicines due during those hours. The full day-care packing list covers the rest.

6. 6

   Eat and drink normally after you go home

   There is no special diet after a routine immunotherapy infusion. Keep drinking water, eat what you can manage, and split the day into small frequent meals if your appetite is low.

Drink water normally, and arrive well hydrated. Two to three glasses in the two hours before you leave home is a reasonable target for most adults. Carry a filled bottle and keep sipping through the visit. Keep drinking normally for the rest of that day and the next. There is no need to flood yourself with litres.

Hydration matters here for a practical reason more than a clinical one. Immunotherapy does not need the heavy pre-hydration drips that some chemotherapy regimens do. What it does need is a vein. Full veins are easier to feel and easier to cannulate, so arriving hydrated often means one attempt instead of three.

• Before you leave home — two to three glasses of plain water in the two hours before travel, along with your normal breakfast.
• During the visit — sip steadily rather than drinking a lot at once; the visit commonly runs several hours and toilet trips are easy to manage with a portable drip stand.
• After you get home — carry on as usual; there is no flushing routine to complete and no minimum litre count for a routine cycle.
• If you are already unwell — vomiting, loose motions or fever before a cycle change the picture; call the team rather than trying to catch up on fluids at home.
• If your fluids are restricted — heart failure, advanced kidney disease and some other conditions come with a daily limit; that limit overrides everything on this page.
• Coconut water, buttermilk, thin dal water, ORS — all reasonable fluids if you dislike plain water, unless your doctor has restricted potassium, salt or sugar.

Loose motions after an infusion are not a hydration problem to solve at home. Repeated watery stools on immunotherapy can be an immune-related reaction and need medical assessment, not just extra ORS. Call the CION helpline on 1800 202 8726 or your treating team the same day, and say you are on immunotherapy.

• A heavy, oily or very spicy meal — hard to sit with for several hours, and indigestion is easy to confuse with a treatment side effect.
• Any food you have never eaten before — if you feel unwell later, nobody can separate the new food from the treatment. Keep infusion day boring.
• Raw, undercooked or roadside food — no cut fruit from carts, no unpasteurised milk or juice, no rare eggs or meat. Wash and peel fruit at home instead.
• Alcohol the night before and on the day — it dehydrates you and can disturb the liver blood tests taken before your cycle, which may push the cycle to another date.
• Several strong coffees on an empty stomach — one usual cup is fine; a caffeine load before a long sitting is not, and it can leave you mildly dehydrated.
• Starting or stopping any supplement on your own — including high-dose vitamin and antioxidant products, which can affect blood results or interact with other medicines.
• Deciding to fast because someone advised it — never do this on treatment without telling your oncologist, and never at all if you take diabetes medication.

If your regimen also includes an oral cancer tablet, ask specifically about grapefruit and about taking tablets with or without food. Those interactions apply to some swallowed medicines rather than to an intravenous drip, and many patients are on both. Whether your cycle is every three weeks or every six weeks does not change any of this advice.

No reliable evidence says so. Fasting, juice cleanses and "immune-boosting" diets are widely promoted online, but research on diet and fasting alongside cancer treatment is still early, and bodies such as ASCO and ESMO do not recommend fasting as part of treatment. Anyone promising a food that makes immunotherapy work is going beyond what is known.

What is well established runs the other way. Losing weight and muscle during cancer treatment is associated with tolerating treatment less well. Eating enough is the goal, not eating less. If your appetite has dropped, that is a reason to ask for help from the nutrition team, not a reason to accept it quietly.

If you have diabetes, do not skip meals before a cycle. Take your medicines as prescribed and carry a snack. Some pre-medication given before certain infusions can push blood sugars up for a day or two, so check your readings more often in that window and tell your oncologist what you see.

If you use ayurvedic, homeopathic or home remedies, you are not doing anything unusual — a great many families in Telangana and Andhra Pradesh do, and it often matters to them. The ask is simple and it is not about belief: bring the actual packets to your next visit and show your oncologist. Some herbal preparations and high-dose supplements can affect liver blood tests or interact with other medicines, and an unexplained abnormal result can delay a cycle. Your team can only work around what it knows about.

If you are travelling in from a district, plan the food before the travel. Eat at home rather than at a bus stand, carry a box and a bottle, and leave enough margin that you are not arriving hungry after four hours on the road. Many families ask whether they can shorten that journey — having immunotherapy closer to home covers what is and is not possible.

If you cannot keep food down, have lost weight without trying, or have had loose motions for more than a day, tell your treating team before the next cycle rather than managing it at the dining table. Those are clinical signals, not diet problems.

• What to Carry to Your Day-Care Infusion — the packing list that goes with this page: food box, water bottle, reports, medicines and what else earns its place in the bag.
• Every 3 Weeks or Every 6 Weeks: Which Schedule and Why — how often you will repeat this day, and what decides the interval between cycles.
• Can I Have Immunotherapy Closer to Home? — for families travelling in from a district, where the eating-and-travel plan matters most.
• Immunotherapy at CION Cancer Clinics — how CION supports patients through eligibility testing, day-care administration and monitoring between cycles.

This page is for general information and does not replace a consultation. Guidance here describes a routine day-care immunotherapy visit; your own appointment slip and your treating oncologist's instruction always come first, particularly if you have diabetes, kidney or heart disease, or a fluid restriction. Visit timings vary by centre, regimen and day, and are not a commitment. Immunotherapy is administered as day care at CION centres; response-assessment imaging is coordinated at partner imaging centres.

Everyone asks about food before the first infusion

It is one of the first questions our day-care nurses hear, and it deserves a proper answer rather than a rushed one. Ask us anything about your treatment day.