A condition in which the body lacks or has lost strength either as a whole or in any of its parts. General asthenia occurs in many chronic wasting diseases, such as anemia and cancer, and is probably most marked in diseases of the adrenal gland. Asthenia may be limited to certain organs or systems of organs, as in asthenopia, characterized by ready fatiguability.
Asthenia is also a side effect of some medications and treatments, such as Ritonavir (a protease inhibitor used in HIV treatment), vaccines such as the HPV vaccine Gardasil and fentanyl patches (an opioid used to treat pain).
The condition is also commonly seen in patients suffering from chronic fatigue syndrome, sleep disorders or chronic disorders of the heart, lungs or kidneys.
Differentiating between psychogenic asthenia and true asthenia with muscular weakness is often difficult, and in time apparent psychogenic asthenia accompanying many chronic disorders is seen to progress into a primary weakness.
Blink-182 (album) has a song called "Asthenia", (about an astronaut in a space capsule contemplating whether his return to earth will even make a difference)