How long before HPMC capsules show results?

This is like asking "How long will it take for the package to arrive?"  It depends not only on how fast the delivery person runs (how quickly the capsule shell dissolves), but also on what you've ordered (how quickly the medication inside takes effect).
The HPMC capsule itself takes about 15 to 30 minutes to "open its doors" in your stomach and release its contents. But for you to actually feel the "effect," it depends on how the ingredients are absorbed by your body.

Step 1: Unpacking the package (Capsule shell dissolution)

This step entirely depends on the performance of the HPMC capsule shell.
Starting time: After swallowing, HPMC capsules usually disintegrate (or break open) in the stomach in about 15 to 30 minutes.
Slightly slower than animal gelatin capsules: Traditional gelatin (made from animal skin) capsules are impatient and dissolve in about 5-10 minutes. HPMC is made from plant fiber and is more "stable," dissolving a few minutes slower, but for most medications and health supplements, this time difference is completely imperceptible and does not affect the final effect.

Step 2: Using the contents (Drug absorption)

Once the capsule shell dissolves, the rest has nothing to do with the shell; it all depends on the ingredients inside.
If it's a painkiller/sleep aid: These Western medicines are absorbed quickly. After the capsule dissolves, you may feel the effect in another 20-40 minutes (a total of about 45 minutes to 1 hour).
If it's a health supplement (such as vitamins): These work subtly. Once the capsule dissolves, the body begins to absorb them, but you won't feel a noticeable "instant effect."
If it's probiotics: These usually take longer. Because many probiotic capsules are specifically designed to be "acid-resistant" (more on this below), they have to survive the stomach acid and reach the intestines before they can work. This process may take 1-2 hours or even longer.
Special case: Deliberately "delayed" capsules
There is a special type of HPMC capsule on the market called **"sustained-release" or "enteric-coated" capsules** (Delayed-Release).
What it does: Some ingredients (such as probiotics, certain enzymes) are particularly sensitive to stomach acid and are destroyed as soon as they enter the stomach. Its performance: This capsule is specially treated and will not dissolve in the stomach even after soaking for an hour. It only opens when it reaches the intestines (where the environment is less acidic). Therefore, if you are taking this type of capsule, the medication may not start to be released until 2 hours later, but this is precisely the effect the manufacturer intended.

How to make it work faster?

Although the capsule shell has its own release rate, your method of taking it can also affect the speed:
Drink plenty of water: Taking it with a large glass of warm water helps the capsule reach the stomach faster, and more water also facilitates its dissolution.
Empty stomach vs. full stomach: Taking it on an empty stomach (if the instructions allow) means the capsule remains the same, but the stomach empties faster, allowing it to reach the intestines and be absorbed more quickly; taking it after a meal means it has to wait in line with the food, so the effect will naturally be slower.