A similar softening of attitudes has been seen in the UK.
In June, 12-year-old Billy Caldwell, who has severe epilepsy, was admitted to hospital after his medical cannabis oil was confiscated. A month later, a special licence to use cannabis oil was granted to seven-year-old Alfie Dingley, who has a rare form of epilepsy.
Following high-profile campaigns, the UK government changed the law to allow doctors to prescribe cannabis products.
As US states such as California found in the 1990s and 2000s, familiarity with medical cannabis can soften attitudes towards recreational use.
But in the UK, the Home Office says the recreational use of cannabis will remain banned, although senior figures, including former Conservative leader William Hague, have suggested a rethink.
Mexico has also had cases of children being denied medical cannabis, but it has also been motivated by the extraordinary violence of its drugs war.
Although marijuana makes up a relatively small share of drug cartel revenues, continuing to ban it is seen as increasingly at odds with reality.
Mexican diplomats warned the US it was difficult to enforce the fight against cannabis when the neighbouring American state of California legalised recreational use.