If you have any health anomalies like hypoglycemia, I’d recommend asking a health professional how fasting may impact the illness. If nothing else, start small with shorter fasts and measure how your body reacts with a glucose/ketone meter. Then, you can slowly and cautiously increase the duration of your fasts depending on how your body tolerates it.
Unless you have a specific medical condition you should be fine. Fasting can be uncomfortable if you’ve never don’t it before and it can FEEL unsafe but isn’t. It helps to clean up your diet alongside fasting because the types of food you eat will impact your fasting. Start with shortening your eating windows and it’ll get easier over time