Canterbury District Health Board is urging people under stress following Christchurch's 6.3 earthquake last month not to "tough it out".
It was normal to be "very stressed" at the moment but anyone concerned about themselves or a family member should talk to their doctor, who could call on mental health and counselling services, the DHB said.
More counsellors were being brought in to help.
The distress could last for days or weeks and it was important for people to allow time to heal physically and mentally, the DHB said.
Support from friends and family was important.
Some people found it helpful to talk while others did not, and either strategy was fine.
People reacted to stress in different ways but common symptoms included: feeling scared, detached, exhausted, sad or guilty: having sleeping problems; having flashbacks; having trouble concentrating and making decisions; anxiety symptoms including loss of appetite, racing heart and rapid breathing; more conflict in relationships.
Grieving was a normal process after such a destructive event, the DHB said.
Reactions could be triggered by aftershocks.
Usually symptoms would lessen over time. Only a very small percentage of people were likely to have ongoing difficulties, the DHB said.
Some things people could do to help were: re-establish routines, try to establish a regular sleeping pattern, eat regularly, restrict intake of drugs, alcohol and caffeine, set realistic goals, keep physically active, and keep busy but also take time to relax.
Children may need more cuddles, support and reassurance. They may be keen to re-enact or draw pictures about the earthquake, which was fine, the DHB said.