Diclofenac absorption depends a lot on the form being used. Oral diclofenac is absorbed through the digestive tract and usually enters the bloodstream fairly well, which is why it can affect the whole body. Food may slow how quickly it is felt, but it does not necessarily stop absorption.

Topical diclofenac works differently. It is absorbed through the skin, so much less reaches the bloodstream compared with tablets. That is why gels and creams are often used when a more local effect is wanted with lower whole-body exposure.

Another important point is that diclofenac absorption is not only about how much enters the body, but also how fast and from where. Tablets, capsules, gels, patches, and injections all create different absorption patterns.

The simplest way to understand it is this: oral forms give broader systemic absorption, while topical forms give more limited, targeted absorption.