The ingredients of juniper berries are believed to have a direct effect on the smooth muscle. This is responsible in the gastrointestinal tract, among other things, for the locomotion of the intestinal contents and can, if it contracts permanently, cause digestive disorders. The berries have antispasmodic action on the smooth muscles. The diuretic effect is attributed to terpinen-4-ol, via irritation and consequent increased blood flow to the kidney tissue.
The above effects have been observed primarily in animal experiments.
Juniper: Side effects and interactions
If juniper berries are used for a longer period of time or in an overdose, irritation of the kidneys, appearance of red blood cells in the urine (hematuria), disorders of the digestive tract, and excitation symptoms in the central nervous system may occur. An overdose can often be recognized by the characteristic violet odor of the urine.
The side effects listed are based on data from 1842 to 44 and have not been reexamined. However, since the relatively high content of α- and β-pinene could cause cell irritation, Commission E lists only dyspeptic complaints as indications for use.
Interactions with other agents are not currently known.
