The Food and Drug Administration (FDA) has extended the amnesty period for people who possess marijuana for medical purposes from May 19 to May 21.
Those who fail to report before the specified deadline will be penalised, despite the fact the government has legalised the medical use of marijuana, which was previously categorised as an illegal narcotic.
The FDA decided to extend the deadline for patients to register for amnesty because May 19 falls on a Sunday.
As May 20 has been designated as a public holiday in lieu of Vesakha Bucha Day, which falls on May 18 this year, the FDA has decided to change the deadline to May 21, said FDA deputy secretary-general, Surachoke Tangwiwat.
Dr Surachoke said that over 6,000 people have registered marijuana in their possession since the amnesty period began on Feb 27.
"We need to know the exact number of patients being treated with marijuana, because it will help us ensure supply can meet demand," he said.
Marijuana extracts are currently being used as an alternative treatment for many conditions.