What if I pay social security but don't pay medical insurance?

You can't pay medical insurance alone.

If the enterprise pays social security, all five insurances need to be paid together, including endowment insurance, medical insurance, work injury insurance, unemployment insurance and maternity insurance.

If individuals pay social security, they can only pay endowment insurance and medical insurance, which is bound. You can't just pay one of them.

Basic medical insurance before retirement, as long as you pay the basic medical insurance, you can enjoy the corresponding treatment according to the regulations. You can't enjoy it without paying.

If you want to continue to enjoy the relevant benefits of basic medical insurance after retirement, the payment period of basic medical insurance shall not be less than 25 years (for men) and not less than 20 years for women.

If the basic medical insurance has been completed for 25 or 20 years before retirement, if you don't continue to pay the basic medical insurance, you won't be able to enjoy the medical insurance benefits.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.