[…] headache, nausea, chest pain, irritability, ataxia, altered mental status, other neurologic symptoms, loss of consciousness, coma, and death; signs include tachycardia, tachypnea
[cdc.gov]
A similar increase in hematocrit can be achieved with erythropoietin injections, which can increase maximal exercise capacity.
[what-when-how.com]
Pulmonary: a) Cyanosis (more common than “cherry red” skin): “Cherry Red” Appearance of Lips and Skin is an insensitive sign associated with carboxyhemoglobinemia b) Dyspnea/Tachypnea
[mdnxs.com]