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What side effects can I expect from Keytruda (Pembrolizumab)?

This Premium Q&A, reviewed and published, features a real conversation between an iCliniq user and a physician.

Patient's Query

Hi doctor,

I am 56 and recently started treatment with Keytruda for lung cancer after my reports indicated high PD-L1 expression. I have had two infusions so far.

Since the last dose, I have been feeling very tired most days, experiencing some body aches, and dealing with a mild skin rash that comes and goes.

My appetite has decreased, and my joints feel stiff in the mornings.

  1. What side effects are expected and which ones are concerning?.

  2. What side effects should I expect from Keytruda (Pembrolizumab)?

  3. Which symptoms are common and can be managed at home, and which ones should I report to my oncologist right away?

  4. Additionally, can side effects appear later after several cycles of treatment, or do they typically show up early on?

Please guide.
Answered by Dr. Amandeep Singh Arneja

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

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Hi,

Welcome to icliniq.com.

I am deeply concerned about your worries.

Starting a medication like Keytruda (Pembrolizumab) can raise many questions, and it is great that you are attentive to how your body is responding.

Keytruda (Pembrolizumab) is an immunotherapy drug that works by activating your immune system to recognize and attack cancer cells. Since it stimulates the immune system, some side effects can occur when the immune system becomes slightly overactive and affects normal tissues as well.

The symptoms you have mentioned, fatigue, mild body aches, joint stiffness, and a mild skin rash, are among the commonly reported side effects of this treatment.

Many patients on immunotherapy experience tiredness, mild joint discomfort, and occasional light rashes. Usually, these symptoms are mild and manageable, but it is important to discuss them with your oncology team during follow-up visits so they can monitor your condition.

In general, symptoms that can often be managed with simple measures include mild fatigue, mild skin rashes, slight joint aches, and decreased appetite. Resting, staying hydrated, gentle physical activity, and basic skin care can help alleviate these issues. However, if the rash becomes widespread, very itchy, or starts blistering, you should inform your doctor.

Certain symptoms should be reported to your oncologist promptly. These include persistent or worsening shortness of breath, new or severe cough, significant diarrhea, severe abdominal pain, yellowing of the eyes or skin, severe weakness, confusion, severe headache, or major hormonal changes such as extreme fatigue accompanied by dizziness. These could indicate immune-related inflammation in organs like the lungs, liver, intestines, or hormone glands, and it is best to address them early.

It is also important to understand that side effects from immunotherapy can appear at any time. Some may manifest early during the initial cycles, while others might develop later, after several treatments, or even after therapy has been ongoing for some time. This is why ongoing monitoring and communication with your oncology team are crucial throughout your treatment.

I hope this helps address your query.

Thank you.

Medically reviewed by iCliniq medical review team
Published At May 9, 2026
Reviewed At May 9, 2026

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

This doctor is not available for online consultations on the platform anymore.

Consult other doctors in the same speciality

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Amandeep Singh Arneja
Dr. Amandeep Singh Arneja

Pulmonology (Asthma Doctors)

Education:

MD RESPIRATORY MEDICINE

Professional Bio:

I am Dr. Amandeep Singh Arneja, a dedicated Chest Physician and Senior Resident in Pulmonary Medicine at Jawaharlal Nehru Medical College (JNMC), Wardha, with extensive training in the management of complex respiratory and critical care conditions. I completed my M.B.B.S. from Universal College of Medical Sciences, Tribhuvan University (2016) and M.D. in Respiratory Medicine from Shri Shankaracharya Institute of Medical Sciences, Bhilai (2025), where I gained hands-on expertise in managing ICU patients, performing advanced diagnostic and therapeutic procedures, and conducting research in pulmonary diseases. My areas of expertise include: Management of asthma, COPD, tuberculosis, and interstitial lung disease Critical care management (ICU care, mechanical ventilation) Pulmonary function testing (spirometry, DLCO) Interventional procedures (thoracentesis, ICD insertion, bronchoscopy) Sleep medicine and polysomnography Research, academic writing, and clinical presentations I hold certifications in Good Clinical Practice and Biomedical Research. I am a proud member of the National College of Chest Physicians (NCCP). Alongside my pulmonary expertise, I have also completed a CPCDM Fellowship in Diabetes from RSSDI, enabling me to provide holistic care for patients with respiratory diseases complicated by diabetes. Currently, I am also pursuing a Fellowship in Critical Care Medicine, which further enhances my ability to manage critically ill patients with respiratory and systemic illnesses. With multiple research publications, conference presentations (NAPCON, SSIMSCON), and a strong academic background, I strive to combine evidence-based medicine with compassionate patient care. My mission is to provide comprehensive, high-quality care to patients suffering from respiratory and lifestyle-related diseases.

This doctor is not available for online consultations on the platform anymore.

Consult other doctors in the same speciality
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