Can hydralazine cause knee pain and weakness be due to hydralazine? I take 10 mg of hydralazine 3 times a day. After about 3 to 4 hours taking it, there is no pain. If I accidentally miss dose, there is no pain. My doctor doesn't think this is due to hydralazine. He says I have arthritis. But when I was taking amlodipine, my angle swelled with severe pain. My doctor didn't think it was due to amlodipine. Only after he did a lot of tests, he agreed it was amlodipine and changed me to hydralazine. What should I do? What are the other side effects that people experience with hydralazine?