H4

H4, H04, or H-4 may refer to:

==Science and mathematics== ATC code H04 Pancreatic hormones, a subgroup of the Anatomical Therapeutic Chemical Classification System Histamine H4 receptor, a human gene Histone H4, a protein involved in the structure of chromatin in eukaryotic cells Hydrogen-4 (H-4), an isotope of hydrogen H4, a symmetry group in the fifth dimension; see H4 polytope H-4, a huge eruption of the Hekla volcano around 2310 BC