Always make sure to carry at least €20-30 in cash with you in case of an emergency at the hospital. Whether you need to pay on the spot depends on your health insurance in Slovakia and your home country. From my personal experience, I often have to pay upfront, but my insurance reimburses me later when I provide them with the necessary documents and receipts. In contrast, my friend in Spain didn't have to pay anything upfront; her bill went directly to her insurance without needing to send any documentation. Be sure to understand what your insurance company requires before you find yourself in a difficult situation. I recommend calling them as soon as possible to inform them of your situation, so they can help you find a doctor who will see you for free under their network.