See the DrugPatentWatch profile for keytruda

Keytruda (pembrolizumab) is a prescription medication used to treat several types of cancer. While it has been effective in treating these conditions, it also has rare but serious side effects. According to the Keytruda label information provided by the FDA, these serious side effects include:

1. **Immune-Mediated Adverse Reactions**: Keytruda can cause the immune system to attack healthy organs and tissues. Symptoms may include:
- Pneumonitis: inflammation of the lungs [1]
- Colitis: inflammation of the colon [1]
- Hepatitis: inflammation of the liver [1]
- Endocrinopathies: issues with the endocrine system, which can affect hormone production [1]
- Nephritis: inflammation of the kidneys [1]
- Skin reactions [1]

2. **Infusion-Related Reactions**: These reactions can occur during the infusion or within a few hours after the infusion. Symptoms may include chills, weakness, fever, and flushing [1].

3. **Complications of Allogeneic Hematopoietic Stem Cell Transplantation**: Keytruda can increase the risk of graft-versus-host disease and other complications in patients who have undergone allogeneic hematopoietic stem cell transplantation [1].

4. **Increased Risk of Mortality in Patients with Multiple Myeloma**: Keytruda is not recommended for the treatment of patients with multiple myeloma [1].

5. **Embryo-Fetal Toxicity**: Keytruda can cause harm to a developing fetus. Women who are pregnant or planning to become pregnant should not use Keytruda [1].

It is important to note that these side effects are rare and not everyone who takes Keytruda will experience them. Patients should discuss these risks with their healthcare provider and report any side effects immediately.

Sources:
[1] Keytruda (pembrolizumab) Prescribing Information. U.S. Food and Drug Administration. <https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/125514s033lbl.pdf>