It can cut pain, but it is also addictive and causes headaches, difficulty thinking, vomiting and muscle twitching.

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People living close to the land have reported headaches, vomiting, sore throats and chest infections.

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Symptoms include mild headaches, muscle pain, fever, a persistent cough and sometimes vomiting and diarrhoea.

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"Symptoms include flu-like symptoms like tiredness, general aches and pains, headaches and fever, as well as loss of appetite, nausea or vomiting, diarrhoea, abdominal pains, jaundice, very dark urine and itchy skin, " he said.

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Sex headaches associated with loss of consciousness, vomiting, stiff neck, other neurologic symptoms and severe pain lasting more than 24 hours are more likely to be due to an underlying cause.

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