From Wikipedia
Apple cider
Apple cider vinegar, otherwise known simply as cider vinegar, is made from
cider or
apple must, and is often sold unfiltered, with a brownish-yellow color; it often contains
mother of vinegar. It is very popular, partly due to its beneficial health and beauty properties. Due to its acidity,
apple cider vinegar can be very harsh, even burning the throat.
If taken straight (as opposed to usage in cooking), it should be diluted (e.g. with fruit juice) before drinking.
[3] Others dilute it with warm water and add some honey.
[4] There have been reports of acid chemical burns of the throat in using the pill form.
[5]