Everyone staying in Switzerland for over 3 months is legally required to have health insurance coverage. If you do not get health insurance, the Swiss authorities will assign you a health insurance plan that can become very expensive, so make sure you do not miss the 3 month deadline! More about Swiss health insurance requirements can be found here.
Basic health insurance covers medical treatment in case of illness and accident.
EU / EFTA students
If you hold a European Health Insurance Card (EHIC) you can apply to be exempt from Swiss compulsory health insurance as long as your policy offers equivalent coverage. Make sure you do this within 3 months of arriving in Switzerland. If you start working, you must take out Swiss health insurance.
Non - EU / EFTA students
You can also apply to be exempt from Swiss compulsory health insurance as long as you have private insurance coverage that is equivalent to that of a Swiss health insurer. If your private insurance does not qualify you must obtain coverage from an authorized Swiss health insurer.
You are free to choose your insurance company, one affordable option for foreign students is swisscare.