The waiting period is the time span in which the insured cannot claim the benefits of health insurance.  For instance, the waiting period for pre-existing diseases in many policies is around 2-3 years.
You suffer from high blood pressure but you manage to find a health insurance policy that covers your pre-existing disease, woohoo! However, there’s a catch. As per your policy guidelines, you have to wait 2 years before you can make a claim for any treatment that occurs because of your high-blood pressure.
What this means is that even if you suffer from a stroke, or any disease that is remotely connected to your current condition before the waiting period is over, your insurance company is not liable to pay for the expenses. Unfortunately, waiting periods are a common clause in most policies. The best choice here is to look for one with no or a minimum waiting period for your ailment.