What are the effects of taking over 1000 mg of Ibuprofen (Advil) each day?

I have Ibuprofen tablets that are 400 mg each, and I usually take between 3–5 tablets every day. Is this dangerous? I’m supposed to avoid medications like ibuprofen because I have only one kidney and I am very underweight, but I seem to be relying on them more and more for pain relief.