USADA said in a statement that Lochte was not using a banned substance but that it prohibits such infusions or injections in excess of 100 mL within a 12-hour period unless received in the course of hospital treatment, surgical procedures or clinical diagnostic investigations.
The 33-year-old's period of ineligibility began on May 24, the date of the infusion, and will keep him from competing in Japan next month at the Pan Pacific Championships and at the world championships in South Korea next July.
Lochte, a 12-time Olympic medallist who made headlines in 2016 over a tale about being robbed and held at gunpoint after a party during the Rio Games which he later admitted was "over-exaggerated", fully cooperated with the investigation.
The swimmer, who won gold in the 4x200 metres freestyle relay in Brazil, missed last year's world championships while serving a 10-month ban handed down by the United States Olympic Committee for his part in the Rio scandal.
Lochte, speaking at a news conference shortly after the USADA announcement, was quoted as saying by the website SwimSwam that he would not let his latest setback keep him from working toward his goal of earning a spot at the 2020 Olympics in Tokyo.
"I wasn't taking anything illegal," said Lochte. "Everything was legal. You can get it at CVS, Walgreens, but there are rules, and you have to obey them... Don't worry. I'm not giving up. I'm going to keep going.
"It's devastating to my family about this because I definitely made myself a better person after Rio, and I was back in training.
"I was feeling good. I was swimming fast. My son being born. Everything was happening. Everything was perfect, and then this happened. And it's devastating."
USA Swimming did not immediately respond to a request for comment.
(Reporting by Frank Pingue in Toronto; Editing by Mark Heinrich and Christian Radnedge)
