Honeysuckle berries only become poisonous to humans when ingested in large quantities; however, they can cause illness. Their toxicity varies on the species, which range from non-poisonous to mildly toxic.
The most common symptom of mild poisoning of honeysuckle berry poisoning is a stomach ache. Usually there are no other symptoms, but mild poisoning can also cause vomiting, diarrhea, sweats, dilated pupils and increased heartbeat. When these berries are ingested in large quantities, respiratory failure, convulsions and coma may occur.
Although some of the honeysuckle berries may be toxic, North Carolina State University Cooperative Extension states that the nectar from the flowers of a honeysuckle plant can be ingested without harm.