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Hiccups happen when the diaphragm is irritated in case of a full stomach or inflammation of membrane surrounding the heart.
Irregular food habits, like eating faster than normal causing the temporary loss of air flow also resuts in short term hiccups.
In most cases they usually subside within a few minutes of rest or with deep breathing exercises. One must inhale as much air as they can, then hold it for some time. Then air must be abruptly released. this must be done for at least ten times or until he is relieved of the hiccups.
Lying on a flat surface for 2-5 minutes, and breathing deeply or drinking a glass of water will do the same trick.
But in case doing them does not help in relieving hiccups and the attack lasts longer than 24 hours, then it is advised to consult a doctor for prescription of medications.
Prescription Medications like chlorpromazine might be very helpful to treat your symptoms.
I hope this helps.