Oronamin C Drink (オロナミンCドリンク, Oronamin Shī Dorinku), produced by Otsuka Chemical Holdings Co., Ltd., (distributed and sold by Otsuka Pharmaceutical Co.) is a carbonated beverage available in Japan. It is commonly called Oronamin C or Oronamin. Its name is similar to the Takeda Pharmaceutical Co. product "Arinamin" and its name comes from Otsuka's own Oronine H Ointment [ja] and one of its ingredients, vitamin C. Oronamin C was named after the Oronine H Ointment in hopes that it would prove to be equally successful.

Oronamin C was introduced in February 1965 and was initially sold in a 120 ml glass bottle sealed with a bottle cap. It contains isoleucine and many other essential amino acids as well as many vitamins such as vitamin B₂, vitamin B₆ and vitamin C. It is not only available in supermarkets and convenience stores in Japan, but also in Otsuka Pharmaceutical Co. vending machines as well. The bottle cap was briefly replaced with a screw bottle cap, but following a nationwide scare during the 1980s regarding a large number of poisoned sealed bottled beverages known as the Paraquat murders, this screw cap was replaced with a one-time "pull-cap," which cannot be re-sealed after opening. Child welfare activist Osamu Mizutani [ja] wrote that the previous screw caps allowed individuals to put in paint thinner and then re-seal the bottles.

In 2000, a "sister" product Oronamin C Royal Polis (オロナミンC ロイヤルポリス, Oronamin Shī Roiyaru Porisu) was introduced. It contains royal jelly and propolis extracts.

While originally sold as a medical health drink with carbonation added, the Japanese Ministry of Health and Welfare filed a claim resulting in the judgement that Oronamin C could not be labeled as a medical health drink. This was a difficult time for Otsuka Pharmaceutical Co., but before long, the Genki hatsuratsu (元気ハツラツ) television advertisement featuring comedian Kon Omura [ja] became recognizable nationwide, and Oronamin C grew into a best-selling health drink in Japan.^{[citation needed]}

In the past, many competing companies have introduced similar health drinks in an attempt to topple the current market oligopoly, but so far, none have been successful (see § Similar products).

Oronamin C's slogan is Genki hatsuratsu (元気ハツラツ). (meaning 'full of vitality') The initial spokesperson for this campaign was comedian Kon Omura. This campaign appeared for about 10 years. In the mid-1960s television advertisements and enamel billboards were used for marketing Oronamin along with other Otsuka Group products. Japanese baseball players from the Yomiuri Giants also promoted Oronamin with the phrase "Oronamin is a small giant!" (オロナミンCは小さな巨人です!, Oronamin Shī wa Chiisana Kyōjin desu!). The tagline "C power becomes G power!" (CパワーがGパワーになる, Shī Pawā ga Jī Pawā ni Naru!) was also used in some advertisements.

The popular Japanese singing group SMAP's songs became featured in Oronamin commercials in 1994 and 1995. Around 2001, a television campaign called "Let's find the Yujiro of the 21st century!" debuted featuring actors from Ishihara International Productions, Inc. Since then, many famous tarento have promoted Oronamin. Hideki Matsui worked as a spokesperson for sister product Oronamin C Royal Prolis during his career with the Yomiuri Giants.

Another version of Oronamin television advertisements were broadcast along with the Giants version, featuring Yūzō Kayama and the Southern All Stars. The campaign slogan was "Clear distinction Oronamin C" (明るくケジメるオロナミンC, Akaruku kejimeru Oronamin Shī).