IV Therapy

The body needs small daily quantities of vitamins and minerals, which are usually obtained from the diet, while intravenous vitamins are used clinically for a few serious conditions such as malabsorption syndromes, Wernicke's encephalopathy, or critical illness. ^[1] Intravenous drips containing high doses of various vitamins and minerals, such as the so-called 'Myers cocktail', have been promoted in popular culture with claims that the intravenous route allows faster absorption than oral intake. ^[1]

Because the intravenous route bypasses the gut, injection of ascorbate raises plasma and tissue concentrations of the vitamin far above what oral dosing achieves, which is the pharmacologic rationale for high-dose infusions. ^[2] Marked differences are recognized in the pharmacokinetics of vitamin C between oral and intravenous administration, so the two routes are not interchangeable at high doses. ^[3] In vitro, vitamin C functions at low concentrations as an antioxidant but may have pro-oxidant, cytotoxic activity at the high concentrations reached only by intravenous dosing. ^[3]

For elective vitamin infusions there is a lack of high-quality evidence that high-dose vitamin drips are necessary or offer any health benefit in the absence of a specific deficiency or medical condition. ^[1] A systematic review of intravenous vitamin C in cancer patients concluded that existing evidence is preliminary and cannot be considered conclusive, though it is suggestive of a good safety profile. ^[4] The use of high-dose intravenous vitamin C cannot be recommended outside of a clinical trial, as current clinical evidence for a therapeutic anticancer effect is ambiguous and based largely on case series. ^[3] In critically ill patients, the most recent large-scale randomized trials could not demonstrate clinically meaningful benefit from intravenous vitamin C, vitamin D, or selenium, and one trial indicated harm from high-dose vitamin C in septic patients. ^[5]

Because high doses of some vitamins and minerals can cause harm, licensed injectable vitamins should not be advertised to the public and should only be supplied and administered by appropriately qualified healthcare professionals. ^[1] A review of anaphylactoid reactions found 23 published cases, 3 of them fatal, of anaphylactoid reactions from intravenous vitamin K, illustrating that the route itself carries risk. ^[6]