Humira, a medication used to treat various conditions such as rheumatoid arthritis, psoriatic arthritis, and Crohn's disease, has biosimilars that may cause similar side effects [1][3]. Biosimilars are biological products that are highly similar to and have no clinically meaningful differences from an existing FDA-approved reference product, in this case, Humira [1].

According to the FDA, the side effects of Humira and its biosimilars can include:
- Infections (upper respiratory, sinus infections, and tuberculosis) [1]
- Headaches [1]
- Reactions at the injection site (redness, rash, swelling, itching) [1]
- Allergic reactions [1]
- Increased risk of certain types of cancer, such as lymphoma or skin cancer [1][3]
- Hepatitis B reactivation [1]
- Heart failure [1]
- Liver problems [1]
- Blood problems (aplastic anemia, pancytopenia, thrombocytopenia) [1]
- Nervous system problems (multiple sclerosis, Guillain-Barré syndrome) [1]

It is important to note that the side effects of biosimilars are expected to be similar to those of the original biologic medication, but there may be some differences due to the manufacturing process [2]. Patients should speak with their healthcare provider about any concerns or questions regarding the side effects of Humira or its biosimilars [3].

Sources:
[1] <https://www.drugpatentwatch.com/p/biologics/tradename/HUMIRA>
[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8014989/>
[3] <https://www.arthritis.org/news/news-and-events/humira-biosimilars>