President Alberto Fernandez ordered all but essential workers to stay home and off the streets.
But he had to change the rules after receiving a message from the mother of a seven-year-old boy who had recently lost his first tooth.
On Twitter Joaquin's mum Cecilia, wrote: "Dear @alferdez, I need to ask if the tooth fairy is among those exempted from quarantine? Joaquin has lost his first tooth and we don´t know if we should leave him a letter (we can´t find the tooth).."
President Alberto Fernandez reassured the boy an hour later that the tooth fairy was indeed on the official list of exceptions to the lockdown rules.
"@littlekbz Cecilita! The tooth fairy can leave rewards for fallen teeth because he is not under quarantine. But the rest of us are... Joaquin should leave the tooth beneath his pillow and enjoy the prize,".
The tooth fairy tradition is practiced in many countries across the world and dates back hundreds of years.