One of the most prevalent home remedies for curing hiccups is to ask someone to startle you. Does it really work?
Hiccups occur when your diaphragm (your main breathing muscle) involuntarily contracts, causing a sudden jolt that closes your vocal chords. Hiccups have many different causes, and there is no scientifically proven cure that works for all cases of hiccups. Most hiccuping bouts are temporary, but in rare cases, hiccups may continue for long periods of time. If your hiccups persist for more than 48 hours, or if they are so severe you are unable to eat or draw a full breath, seek medical assistance. Physicians may be able to offer muscle relaxants to stop chronic hiccups, or surgery may be required to treat the underlying cause.
According to an article published by the Journal of Clinical Gastroenterology, hiccup remedies that interrupt your breathing rhythm are often effective at stopping hiccups. This offers some evidence as to why having someone startle you may stop your hiccups. The human startle response, also known as the fight or flight response, occurs when the parasympathetic nervous system is activated. Adrenaline is released into the bloodstream to prepare for fight or flight, and the adrenaline causes an increase in heart rate, and an increase in breathing- often a sharp intake of breath, followed by a pattern of quick, shallow breathing. Because being startled changes your breathing rhythm, it may be an effective way to stop hiccups.
The trick to this technique is that you need to be genuinely startled. If you ask someone to startle you, you will expect it, and your body will not respond in the same way as it would to an unexpected startle. Your friend needs to wait a few minutes after you ask them to startle you and wait for you to be distracted before causing the startle. A sudden loud sound is often the easiest way to activate the startle response.
The Merck Manuals Online Medical Library points out that hiccups often occur when carbon dioxide levels are lower than normal, and many home remedies for curing hiccups involve raising carbon dioxide levels. If being startled does not cure your hiccups, try one of the carbon dioxide methods, such as breathing into a paper bag or holding your breath.
Journal of Clinical Gastroenterology; Hiccups: Causes and Cures; James H Lewis, M.D. http://journals.lww.com/jcge/Abstract/1985/12000/Hiccups__Causes_and_Cures.21.aspx
Mayo Clinic; Hiccups
The Merck Manuals Online Medical Library; Movement Disorders; Hiccups: Spasms of the Diaphragm
Mind/Body Education Center; The Fight or Flight Response; Neil F. Niemark