the cure is worse than the disease

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• phrase The medical treatment for an illness produces a worse net result than the illness does (or threatens a non-negligible risk of doing so), especially via adverse effects.
• phrase figuratively The solution or proposed solution to a problem produces a worse net result than the problem does (or threatens a non-negligible risk of doing so), especially via unintended consequences.