Lung - NSCLCTaken continuously — no infusion cycle8 effects documented
Immunotherapy that helps your own immune system fight the cancer. Most people tolerate it well, but the immune system can occasionally inflame organs (lungs, bowel, liver, hormone glands, skin). Reporting new symptoms early lets your team treat these quickly.
Pembrolizumab is immunotherapy given every 3-6 weeks. Its main effects are IMMUNE-RELATED — the immune system can inflame almost any organ, and this can happen ANY time, even months after treatment. Onset is measured in weeks-months, not infusion days; there is no blood-count nadir cycle.
Get help straight away — this is true on any regimen, on any day.
A temperature of 100.4°F (38°C) or higher during treatment can mean a
serious infection while your blood counts are low. Call your team or go to the ER — do not
wait it out.
Also urgent: trouble breathing or chest pain · swelling of the face, lips or throat ·
new confusion or fainting · shaking chills · not being able to keep fluids down.
This is standing guidance shown to everyone. Nothing on this page is based on anything
about you, and nobody is monitoring you.
One of the 8 entries below is marked provisional.
They are shown because leaving them out would be its own distortion, but they have not yet
been checked against the source document by a person, and they are not presented as
authoritative. Every provisional entry is labelled where it appears.
What is reported
This regimen is taken continuously, so effects are described in the terms their sources use rather than by cycle day.
Immune-related pneumonitis (lung inflammation)
any time on/after treatment, often weeks-months
The immune system can inflame the lungs, causing new or worsening cough, breathlessness, or chest discomfort. It's uncommon but important — report breathing changes promptly; it's treated by holding the drug and giving steroids.
Call your team urgently: New or worsening breathlessness or cough — contact your team urgently.
reported by about 3.4% of people; severe in 1.2% · from Pembrolizumab
Immune-related colitis (bowel inflammation)
any time on/after treatment, often weeks-months
The immune system can inflame the bowel, causing diarrhea, cramping, or blood/mucus in the stool. Report new or worsening diarrhea early — untreated it can become serious; it's treated with steroids.
Call your team urgently: Diarrhea with blood/mucus, severe cramping, or more than a few extra stools a day — call urgently.
reported by about 1.7% of people; severe in 1.1% · from Pembrolizumab
Immune-related hepatitis (liver inflammation)
any time on/after treatment
The immune system can inflame the liver, usually seen first as rising liver blood tests. Report yellowing of the skin/eyes, dark urine, or belly pain; your team monitors bloodwork.
Call your team urgently: Yellowing of skin/eyes, dark urine, or severe belly pain.
reported by about 0.7% of people; severe in 0.5% · from Pembrolizumab
Thyroid problems (hypo- or hyperthyroidism)
weeks-months into treatment
The most common immune effect: the thyroid can become underactive (tiredness, cold, weight gain) or overactive (racing heart, weight loss). Underactive thyroid is often permanent and treated with a daily thyroid pill.
reported by about 8% hypothyroid (hyperthyroid ~3.4%) of people; severe in 0.1% · from Pembrolizumab
Other hormone-gland problems (pituitary, adrenal, type 1 diabetes)
any time on/after treatment
Less commonly, the immune system affects other hormone glands — the pituitary or adrenal glands (severe tiredness, low blood pressure, dizziness) or the pancreas (new diabetes with thirst/frequent urination). These can be serious and often need lifelong hormone or insulin replacement.
Call your team urgently: Fainting, severe weakness, or confusion — seek urgent care.
reported by about ~0.2-0.8 each% of people · from Pembrolizumab
Severe skin reactions
any time on treatment
Most skin effects are mild (rash, itch), but rarely a serious blistering/peeling reaction can occur. Report a spreading rash, blisters, or peeling — especially with mouth/eye involvement.
Call your team urgently: Blistering, peeling, or a rash with mouth/eye sores — seek urgent care.
severe in 3.9% · from Pembrolizumab
FatiguePROVISIONAL
Tiredness is common. If it's marked, your team may check your thyroid and adrenal function, since a hormone problem can cause it.
reported by about 20-40% of people; severe in 1.3% · from Pembrolizumab
Infusion reaction
during the infusion
An uncommon reaction during the infusion (chills, flushing, breathlessness). Tell your nurse right away; it's managed by slowing or pausing the drip.
reported by about 0.2% of people · from Pembrolizumab
Where this comes from
S1. Pembrolizumab (Keytruda) FDA prescribing information (pooled safety, n=2799) — FDA label
S2. Reck M, KEYNOTE-024 (pembrolizumab vs chemo, PD-L1 high NSCLC) (2016) — PMID 27718847
A window appears here only where a retrievable document ties it to a drug in
this regimen. Where nothing could be found, the window was removed rather than estimated —
so a missing time is an honest gap, not an oversight.