It is also sometimes called erythrocytosis, which means too many red blood cells. And it used to be called polycythaemia rubra vera or PCRV. PV is a type of rare blood disorder called a myeloproliferative neoplasm.These are conditions that cause an increase in the number of blood cells.t is also sometimes called erythrocytosis, which means too many red blood cells. And it used to be called polycythaemia rubra vera or PCRV. PV is a type of rare blood disorder called a myeloproliferative neoplasm.
Acetaminophen -- best known as Tylenol in the United States -- does not appear to help ease lower back pain and offers little relief for the most common form of arthritis, according to a new report.
Itâs not a good idea to take it long-term, according to our medical advisors. Tylenol PM contains two medicationsâthe pain reliever acetaminophen and an antihistamine (diphenhydramine) to help with insomnia. High doses of acetaminophen can cause liver damage and the risk increases if you consume alcohol. Possible side effects of diphenhydramine include daytime sleepiness, confusion, constipation, dry mouth, and urinary retention and it can worsen your sleeping problems when taken too often.