Historically, ageing has been regarded as a biological process that is unalterable. Although it is not possible to halt or reverse this process, medical scientists are currently attempting to extend lifespan and healthspan by developing treatments that ensure that the hallmarks of ageing do not resemble someone who is elderly. The accumulation of senescent cells is a hallmark of biological ageing. It is speculated that once the volume of senescent cells exceeds a safe therapeutic threshold the possibility of developing age-associated diseases increases. Senotherapeutic medications, otherwise known as senotherapy, aim to keep the volume of senescent cells below this threshold. These medications either eliminate senescent cells (i.e., senolytic medications) or prevent healthy cells from becoming senescent (i.e., senomorphic medications). While preliminary research shows that senotherapy is a promising strategy for increasing both human lifespan and healthspan, there nevertheless remains many unanswered questions. This book summarises our current research about senescent cell accumulation and age-associated diseases, human trials of senotherapeutic medications, and topics about senotherapy that require more research.