Canterbury District Health Board says people in Christchurch whose well-being depends on medication must ensure they get it.
The DHB says it has treated several diabetics who have stopped taking their prescribed medication.
DHB chief executive David Meates says this cannot continue to happen.
He says the majority of pharmacies throughout the region are fully operational and they will dispense medicine without a subscription for a further seven days.
Mr Meates says anyone on hospital-based medication for mental health issues should contact their case manager or phone 0800 920 092.
Meanwhile, Healthcare New Zealand is asking all of its Christchurch clients and staff to urgently contact the company.
The community healthcare service provider has been trying to get in touch with about 2500 people since the quake.
Healthcare New Zealand's Lisa Thompson says they have been able to reach 1700 staff and clients but have concerns for some people they haven't been able to contact.
Ms Thompson is urging those people to call 0800 227 348 to let Healthcare New Zealand know they are fine or whether they need assistance.