Depending on context, 'ingestion' can imply various methods of intake, not limited to eating or drinking. The ingestion of medication might involve inhalation as well as swallowing pills.
Pro Tip 2/3
Not for Breathing
'Ingestion' specifically means taking in through the digestive system; it's not used for breathing. The ingestion of oxygen isn't correct; instead, use 'respiration' or 'breathing.'
Pro Tip 3/3
Usually Voluntary
Ingestion often implies a deliberate act, though it can be involuntary, like accidental poisoning. The baby's accidental ingestion of the cleaner immediately prompted a call to poison control.