Italy joining the Central Powers

What would happen if Italy joined the Central Powers?

Japan would probably be invited into Mediterranean operations earlier, while poor Italian-Austrian coordination would complicate the opposing coalition.

Britain and France would seek additional naval help against Italy in this counterfactual. The Japanese Navy would probably enter the Mediterranean earlier and cooperate with the British and French forces. Relations between Italy and Austria are treated as an obstacle to effective coordination. The precise outcome remains open because that relationship creates further problems.