Why is it so much harder to swallow pills than it is to swallow food?

Question

I don't have any real trouble swallowing pills, and I do it several times a day. But when I try to swallow a pill without food or water in my mouth, it is a bit tricky. We're not talking about huge horse pills either, just regular, relatively small pills. I can swallow a whole raw oyster, which is the size of hundreds of pills combined, but a single little capsule or tablet is too much for me to consume without food or water?

It feels like I am struggling to convince my tongue and throat to cooperate with me, and they don't trust my judgment in choosing what I should and shouldn't swallow.

What is going on here? Is there some sort of physiological explanation for this?

Note: I am fully aware that my tongue and throat don't have minds of their own, and are incapable of trusting or mistrusting me. I am merely trying to explain what it feels like.

Answer 1

The human (and other animals) upper digestive tract is 'designed' to ingest relatively large (compared to most pills), soft, moist boluses. The muscles of the tongue and pharynx can propel these kinds of objects (including liquid) into the esophagus with ease, unless there is some specific pathology at work. Chewing also tends to naturally push food toward the swallowing position.

The tablets and capsules you asked about, on the other hand, tend to be dry and hard and are not chewed. There is little for the tongue and throat muscles to 'grab' as they try to push the object back to where it can actually enter the esophagus. They also tend to get stuck because of their dryness.

Once you have actually swallowed a pill without water or food to help it along, the difficulty for the ingestion process does not end. The esophagus also has difficulty pushing them down to the stomach, though gravity helps. Sometimes they do end up lodged in the esophagus where they ultimately dissolve and pass on down, but not before they may have caused damage to the lining of the esophagus from their caustic properties or just from the pressure of it's presence.

The struggle is your tongue and throat telling you, "You are asking me to do something I wasn't designed to do!"

Anatomy and Physiology of Feeding and Swallowing – Normal and Abnormal is an excellent discussion of human swallowing by Koichiro Matsuo, DDS, PhD and Jeffrey B. Palmer, MD.