Is it normal to feel extremely lightheaded during an asthma attack?

Yes some may: Some people with asthma depending on the severity of the asthma attack may feel lightheaded, and sometimes it may be due to therapy.

Hyperventilation: Frequently during an asthma attack people breathe fast. This rapid respiratory rate leads to hyperventilation. Hyperventilation can result in feeling light headed.

Yes: Decreased oxygenation of the brain cells due to asthma attack (not enough oxygen in the lungs to sufficiently oxygenate the circulating blood) can possibly cause lightheadedness.