Keytruda® (Pembrolizumab) IV Infusion

What pembrolizumab is and how it works

Keytruda is the brand name for pembrolizumab, an immunotherapy drug rather than a chemotherapy drug. The distinction matters, because it explains almost everything about how treatment feels and what can go wrong.

Chemotherapy kills cells that divide rapidly. Cancer cells divide rapidly, so chemotherapy works, but so do hair follicles, bone marrow, and the lining of the mouth and gut, which is why chemotherapy causes hair loss, low blood counts, and mouth sores. Pembrolizumab does not attack cells at all. It works on your immune system instead.

Your T-cells carry a protein on their surface called PD-1, which functions as an off switch. When something binds to PD-1, the T-cell stands down. This switch exists for a good reason: it stops your immune system from attacking your own healthy tissue. Many tumors survive by exploiting it, coating themselves in the proteins that flip that switch, which effectively paralyzes the immune cells that have found them.

Pembrolizumab is an antibody that covers PD-1 so the tumor cannot reach it. The off switch stops working, the T-cells around the tumor reactivate, and your own immune system does the work of attacking the cancer. This is why responses to immunotherapy can last a long time after treatment ends, and it is also why the side effects are what they are. A less restrained immune system is better at attacking tumors and also more likely to attack healthy organs.

What pembrolizumab treats

Pembrolizumab is FDA-approved across a wide range of cancers, including melanoma, non-small cell lung cancer, head and neck cancer, kidney cancer, bladder and urothelial cancer, triple-negative breast cancer, endometrial and cervical cancer, gastric and esophageal cancer, liver and biliary tract cancer, Merkel cell carcinoma, cutaneous squamous cell carcinoma, classical Hodgkin lymphoma, and primary mediastinal large B-cell lymphoma. It is used alone in some settings and combined with chemotherapy or targeted drugs in others.

It also carries an unusual category of approval that is worth understanding. For certain tumors, eligibility depends not on where the cancer started but on its genetics. Tumors that are microsatellite instability-high or mismatch repair deficient, and tumors with a high tumor mutational burden, may qualify for pembrolizumab regardless of which organ they arose in. This is why your oncologist may order biomarker testing on your tumor tissue before starting. That testing is also frequently what an insurer wants to see before authorizing the drug.

Your oncologist determines whether your specific diagnosis and biomarker results fit an approved indication. We are not able to answer that question for you.

Dosing and schedule

Pembrolizumab uses flat dosing for adults, meaning the dose is the same regardless of your weight. Your oncologist selects the schedule.

Who	Dose	How often	Infusion time
Adults, most indications	200 mg	Every 3 weeks	30 minutes
Adults, most indications	400 mg	Every 6 weeks	30 minutes
Pediatric patients	2 mg/kg, up to a maximum of 200 mg	Every 3 weeks	30 minutes

There is also a subcutaneous co-formulation, Keytruda Qlex (pembrolizumab with berahyaluronidase alfa), approved by the FDA on September 19, 2025, which is injected into the thigh or abdomen over one to two minutes instead of infused. It uses different doses and is not interchangeable with the intravenous form. CarePoint currently administers the intravenous formulation; call us if your oncologist is considering the subcutaneous version.

What a visit looks like

1. Before your first visit. We verify your benefits and complete prior authorization, confirm your orders with your oncology office, and review your full medication list including over-the-counter drugs and supplements. Tell us if you have an autoimmune condition, have had an organ transplant, or take steroids, since your oncologist needs that information.
2. Labs and vitals. Pembrolizumab requires periodic monitoring of liver enzymes, kidney function, and thyroid function. Depending on your oncologist's plan, labs are drawn a few days ahead or the same day. Results are reviewed before the infusion is released.
3. Access. We use your port if you have one, or place a peripheral IV. Wear a top with sleeves that roll up easily, or a loose neckline if you have a chest port.
4. The infusion. The dose is diluted and infused over 30 minutes through a dedicated line with an in-line filter. Nothing else is given through that line at the same time. Vital signs are checked before, during, and after.
5. Observation and records. You are observed afterward, longer on your first visit than on later ones. Infusion records go back to your oncology office. Most patients drive themselves home after the first visit or two, but bring someone with you the first time, because nobody knows yet how you will feel.

Practical notes from patients who have done this: dress in layers, because infusion rooms run cold. Bring water and a snack. Plan for roughly two hours even though the drug itself takes thirty minutes.

Side effects: what makes immunotherapy different

Most people tolerate pembrolizumab better than chemotherapy. The common effects are fatigue, itching, rash, joint aches, diarrhea, and nausea, and most are mild.

The category that requires your attention is different. Because the drug releases a brake on the immune system, the immune system can begin attacking healthy organs. These are called immune-related adverse events, and they behave unlike chemotherapy side effects in three ways that matter to you.

They can affect any organ. Lungs, colon, liver, thyroid, adrenal and pituitary glands, pancreas, kidneys, skin, heart, nerves, and brain have all been affected.

They follow no schedule. Chemotherapy side effects arrive on a predictable cycle. Immune reactions can appear after the first dose, after a year of uneventful treatment, or months after your final infusion.

They look like ordinary illnesses. Immune pneumonitis looks like pneumonia. Immune colitis looks like a stomach bug. Adrenal insufficiency looks like exhaustion. The treatment is nearly opposite — steroids to calm the immune system, rather than antibiotics — so being mistaken for a common infection is the central risk.

The figures below come from the pembrolizumab prescribing information, pooled across 2,799 patients who received the drug as a single agent.

Organ system	What you might notice	Reported rate
Lungs (pneumonitis)	New dry cough, shortness of breath with ordinary activity, chest discomfort	3.4% — higher (6.9%) with prior chest radiation
Colon (colitis)	More frequent or looser stools than usual, cramping, blood or mucus in stool	1.7%
Liver (hepatitis)	Usually no symptoms at all; found on routine labs. Sometimes yellowing of eyes or skin, dark urine	0.7%
Thyroid	Fatigue, cold or heat intolerance, weight change, racing heart	Underactive 8%, overactive 3.4%
Adrenal / pituitary	Severe fatigue, dizziness on standing, nausea, persistent headache, vision change	Adrenal 0.8%, pituitary 0.6%
Pancreas (new diabetes)	Intense thirst, frequent urination, rapid weight loss, confusion	0.2%

Thyroid problems are the most common of these and are also the most manageable. They are usually treated with a daily thyroid hormone pill, and treatment often continues. Rarer events involving the heart, brain, or adrenal glands are medical emergencies.

Carry your immunotherapy wallet card

If you go to an emergency room or urgent care while on pembrolizumab, the single most useful thing you can do is tell the clinician, before anything else, that you are on a checkpoint inhibitor. A physician who does not know this may reasonably treat your cough as pneumonia and prescribe antibiotics, which will do nothing for immune pneumonitis while the inflammation continues.

Most patients receiving immunotherapy are given a wallet card that states which drug they are on and lists warning signs for the treating clinician. Keep it in your wallet or as a photo on your phone, and show it at every unscheduled medical visit. Because immune reactions can surface long after your last dose, keep carrying it for several months after treatment ends. If you were not given a card, ask your oncology office.

Merck's KEY+YOU patient support program offers educational materials and symptom-tracking tools for people prescribed Keytruda and can be reached at 855-398-7832.

Insurance and prior authorization

Pembrolizumab is an expensive specialty drug, and essentially every plan requires prior authorization. Approval usually depends on your documented diagnosis, prior treatments, and for many indications the results of biomarker testing your oncologist orders on your tumor tissue, such as PD-L1 expression, microsatellite instability, or mismatch repair status.

We verify your benefits and pursue authorization before your first infusion, so you learn what you will owe beforehand rather than in a bill afterward. If coverage is denied, we will tell you directly and work with your oncology office on next steps. Our prior authorization page explains the process in more detail.

Information for referring oncologists

We accept pembrolizumab referrals from oncology practices across Northeast Ohio and function strictly as the administration site. What we provide:

• Administration of physician-ordered pembrolizumab, 200 mg every three weeks or 400 mg every six weeks, infused over 30 minutes through a dedicated line with a 0.2 to 5 micron in-line filter, with no co-administration through that line.
• Port and peripheral access, vital signs before, during, and after, and management of infusion-related reactions on site.
• Pre-infusion review of orders and laboratory parameters against the hold criteria you specify.
• Infusion records and any same-day laboratory results returned to your office after each visit.
• Benefits verification and prior authorization support, completed before the first dose.
• Scheduling coordination around your imaging and follow-up visits.

Immune-related toxicity assessment, steroid management, and all hold or discontinuation decisions remain with your practice. We will contact you with any concern raised at the chairside and will not initiate treatment changes. To send orders or discuss a patient, call (216) 755-4044 or fax 330-967-0571.

Common questions

Getting started

If your oncologist has prescribed Keytruda and you would like to receive it closer to home, call (216) 755-4044 or send us a message. We will coordinate orders with your oncology office, verify your benefits, and schedule your first infusion.

CarePoint Infusion Center
23215 Commerce Park, Suite 318, Beachwood, OH 44122
Phone (216) 755-4044 · Fax 330-967-0571 · [email protected]
Monday–Thursday 8:00 AM–5:00 PM, Friday 8:00 AM–12:00 PM

Related pages

• All infusion services at CarePoint
• Biologics: what they are and how they work
• IVIG therapy
• Pemgarda COVID-19 prevention for immunocompromised patients
• How prior authorization works
• What is infusion therapy?