Many medical marijuana users have developed side effects such as nausea, vomiting and hallucination, the Krabi Public Health Office revealed Friday.

Thailand has legalized medical marijuana in response to findings that are helpful to patients of many diseases such as cancer and Alzheimer’s.

Between February and May, marijuana users were offered amnesty and encouraged to come forward and be registered as legal users of the substance for medical reasons.

The office’s deputy chief Pinyo Tarangkon said 158 medical-marijuana users had registered with the authority in the southern province of Krabi.

“I’ve received reports that most users did not consult doctors and have developed side-effects,” Pinyo said.

He advised patients to seek advice from pharmacists and Thai traditional doctors with special training on how to use medical marijuana. “

Although extracts from marijuana can ease pain, they may not be suitable for some patients,” he said.

Source