Social security
To be reimbursed for your medical expenses, you must be insured under the French social security system, which will reimburse the mandatory portion of your medical expenses.
You will be insured depending on your professional situation: student, employee, independent worker… You must have a residence permit for France. To know more about it, go on fr.
Any person living in France legally and regularly (which is someone who is holding a residence permit or who has started the procedure to get one and who has been living in France for at least three months) will at least be covered by the universal social security (in French, protection universelle maladie – PUMA).