Apple cider vinegar has few side effects and is generally considered safe for adults to consume or use externally, according to WebMD. Side effects, which are rare, include lowered blood sugar levels in diabetics, lowered potassium levels and interactions with some medications.
Side effects are mostly due to drug interactions. Digoxin, sold as Lanoxin, insulin and diuretic drugs interact with apple cider vinegar. Taking too much apple cider vinegar can cause decreased levels of potassium in the body. Water pills, or diuretic medications, also reduce potassium in the body, so taking these in conjunction with apple cider vinegar can cause potassium deficiency. There is insufficient research on apple cider vinegar use during pregnancy, so it is recommended to avoid using it during pregnancy and breastfeeding.
Apple cider vinegar is used as a home remedy for numerous symptoms, including slow digestion, leg cramps and pain, upset stomach, sore throat and high blood pressure, notes WebMD. It is also used by some as a potential remedy for infection, osteoporosis, acne, sunburn and shingles. Others use it for insect bites, dandruff and vaginal infections.
Apple cider might lower blood sugar levels in diabetics, states WebMD. It reportedly does this by changing the way that food is absorbed by the gut. Apple cider vinegar may also prevent the breakdown of some foods. However, lowering blood sugar levels can affect other diabetes medications, so levels should be monitored closely and in coordination with a physician.
Although apple cider vinegar is consumed as a home remedy for many ailments, WebMD stresses that there is insufficient evidence to rate apple cider vinegar for most of these uses.