Can taking 4 excedrin every morning hurt me?

Not a good idea: You didn't say why you are doing this. 4 regular Excedrin gives you the maximum recommended dose of acetaminophen, which if taken frequently can harm your liver. You are also getting 1000mg. Of aspirin, which is more than the 650mg. Recommended dose. This interferes with blood clotting and can cause ulcers. Finally you are getting about as much caffeine as 4 cups of coffee. Not recommended.

Excedrin has ASA: Excedrin has aspirin. This can cause large and 'silent' ulcers. The Aspirin both causes the ulcer and masks the symptoms - i.e. They are painless until they bleed. The biggest ulcers i've seen were from excedrin... I suggest you get a better solution for the problems for which you're taking the excedrin...