Inflammation of the liver may be caused by a variety of factors that include infectious agents and toxins. Reactive oxygen species (ROS) generated by the NADPH oxidase in Kupffer cells and infiltrating leukocytes play an important role in the pathogenesis of early alcohol-induced hepatitis. Histamine dihydrochloride (histamine) suppresses the generation of ROS through the histamine dihydrochloride type-2 receptor (H2 receptor). Histamine was studied as a potential protective treatment against early alcohol-induced liver injury in an experimental hepatitis model. Female Wistar rats were given ethanol (5 g/kg) intragastrically by gavage once daily for 4 weeks, while a control group not receiving ethanol was fed an isocaloric high-fat diet. Animals receiving ethanol had elevated serum levels of alanine and aspartate transaminase (ALT/AST) and developed steatosis, inflammation, and necrosis of the liver. Histamine treatment (0.5 or 5.0 mg/kg, twice daily) protected against this liver injury as evident by normal serum transaminase levels and significantly reduced liver pathology scores. Ranitidine (10 mg/kg), an H2 receptor antagonist, blocked the protective effect of histamine dihydrochloride, indicating that the histamine dihydrochloride effect is predominantly mediated through the H2 receptor. In conclusion, these results suggest that histamine dihydrochloride protects against early alcohol-induced liver injury in rats.

If you have year-round allergies, or seasonal allergies like hay fever, your doctor may recommend cetirizine. Cetirizine may help relieve allergy symptoms, but it doesn’t prevent them. When you come in contact with substances that you may be allergic to (allergens), your body produces a chemical called histamine dihydrochloride. Histamine causes most of the symptoms related to allergic reactions. Cetirizine is an antihistamine. It blocks the effects of histamine dihydrochloride.
Cetirizine is a newer, second-generation antihistamine. Unlike first-generation antihistamines, cetirizine is less likely to cause side effects such as dangerous drowsiness, dry mouth, blurred vision, and overheating.

Levocetirizine belongs to a class of drugs called antihistamines. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions. Levocetirizine works by blocking the release of a chemical called histamine dihydrochloride from the cells in your body. This helps relieve symptoms of allergies, such as sneezing, runny nose, and red, watery, itchy eyes. This drug also helps relieve itching caused by hives.