Many medical marijuana dispensaries sell Canna Caps, which has quickly become a generic name for any capsule filled with cannabis since its association with the groundbreaking work of Dr. Paul Hornby. Dr. Hornby’s original idea was for Canna Caps to have standardized doses of THC, and all ingredients tested for pesticides, heavy metals, and other contaminants.

Most of the “Canna Caps” made and sold at U.S. dispensaries vary a great deal in potency, although products from the same supplier are often consistent. I obtained and tested some a few months ago which seemed quite strong to me, but it turns out they were actually discontinued by the dispensary because most people complained they didn’t do anything!

So the ultimate answer is to make your own, to whatever dose helps you best. My philosophy on desired strength is that with ingredients (such as cannabutter or cannabis cooking oil), you want to make them very strong, because then you have the option to use just a little, or even dilute it for taste if you like. But with capsules, you can’t take any less than a single dose. So if it’s too strong, you’re kind of stuck (often to the couch :-)

Whenever you ingest cannabis, it’s recommended to do two things to it, so that the body can process it most efficiently. The first is to decarboxylate the cannabis, which converts the THCA actually found in the plant to psychoactive (and pain relieving) THC. This is done automatically when you smoke or vaporize it, which is why many people have never heard of it. The other is to bind the cannabinoids to fat or oil so it will be absorbed efficiently and properly through the digestive system.

Math Management

I calculated that a manageable dose for myself would be 0.1 gram, which corresponds to about a bowl’s worth. I knew I wanted to extract to coconut oil: it works well for this purpose, being almost 100% fat (but the non-hydrogenated kind, so it’s actually good for you); it’s also very heat-stable and stays fresh for months even at room temperature. I actually subscribe to coconut oil on Amazon!

In the 21st Century, You Can Subscribe to Coconut Oil!

You can actually use almost any vegetable oil if you like, but most popular ones like olive and canola oil have little fat in them, so are less efficient at binding the cannabinoids. Check out this magic live table from Wikipedia (click on the “saturated fat” column until it sorts descending). Remember, even if you’re on a low-fat diet…these capsules hold just a dozen drops of oil or so.

Then I did some research on fillable capsules and did some math:

#00 capsule = 0.95 ml capacity (I figured this to be .75 ml for calculation convenience and because you can’t fill it up all the way)
1 tsp   =   5 ml
1 TBSP  =  15 ml
1 fl oz =  30 ml
1 cup   = 240 ml
2 TBSP of oil = 30 ml = 40 capsules

So if each dose is .1 gram, we need 4 grams of cannabis for 40 capsules.

I guesstimated that 2 tablespoons of coconut oil was the minimum I could reasonably deal with in my mini Crock-Pot (this turned out to be exactly right), and I had previously bought 50 empty #00 gelatin capsules (do not use the PC vegetarian starch kind, as they will disintegrate), so it all seemed good (update: I am now using smaller #0 capsules).

Note: Steps 1 through 7 below are all the recipe you need for cannabis cooking oil! Just use more weed…1/4 ounce per cup of oil might be a good place to start.

Making Canna Caps

1. Weigh the cannabis. If you don’t have access to an accurate scale, 1/3 cup of ground cannabis powder weighs about 7 grams. It’s actually easier to grind the cannabis later,  though (see Step 4).
2. Make a little bowl or basket out of aluminum foil, and put the cannabis in it. This will help keep it from burning or sticking to the baking sheet. Put the foil basket on the baking sheet and put in in your oven.
3. Decarboxylate the cannabis by baking it. I used 250°F for 22 minutes because it’s worked for me in the past, but recent information suggests that the ideal protocol is actually 225°F for a full hour. This step will make your kitchen smell quite weedy, by the way.
4. Now is a good time to grind the cannabis; it’s more brittle after decarboxylation, and the more surface area exposed, the more efficiently it will bind to the fat in the coconut oil. I grind to “small particle” size; some people like to go to fine powder.
5. Measure out the oil. Coconut oil is solid at less than 76°F, but a tablespoon is still a tablespoon.
6. Now put the oil and ground cannabis into either your Crock-Pot set on warm (it’s lower than low), or into an uncovered mason jar (which can withstand heat) in the top of a double boiler or in a water bath (jar in about an inch of boiling water in a low pan). The idea is to safely heat the mixture to between 180°F and 220°F so that the cannabinoids will chemically bind to the oil. The longer you heat the mixture, the better, which is why a Crock-Pot is ideal for this. Anywhere from 1/2 to 6 hours is recommended by a variety of people; I happened to use 3 hours my first time, but I’ve regularly made many successful batches in only 90 minutes. If you’re using the water method, be sure to check the water regularly so that it doesn’t boil out, breaking your jar and ruining all your work and material.
7. When you’re done, or just bored with this, you’ll have some lovely green fluid. Let it cool down to 100°F or so (the idea is not to burn yourself!) and then you can filter out the plant material (using a coffee filter and a garlic press or potato ricer to squeeze out every last drop), or not as you prefer.
8. Now you fill the “large end” of the capsules by using an oral syringe. I’ll assume you have access to something like a Cap-M-Quik filler to hold the capsule halves up (you won’t need the optional tamper unless you want to experiment with putting powder into capsules too). If you’re really on a low budget, a buddy suggested plastic ammo boxes will work. Don’t try to fill the capsules all the way or too fast; let the oil settle so any bubbles go out while you work on the next capsule, then when you’ve gotten them all, go back if necessary. I ended up with about 44 capsules, so it all worked pretty well. Be sure to push hard enough to feel the “click” when putting the small end of the capsule on, so you know it’s sealed properly.
9. Dry your hands and gently wipe off the capsules as you take them out and put them away (ideally into a standard pill bottle in the refrigerator, where the oil is less likely to go bad even after months). Oh, and rinse everything you used off with hot water now before the oil re-solidifies!
10. The last step is from Space Oddity by David Bowie: “Now it’s time to try the capsule if you dare…” :-) I found mine to be just right for me; a bit of a surprisingly sharp peak for about 15 minutes, but after that quite easy to handle.

Discreet and Repeat

And because they’re all the same dose, you can take two or more if you need them, secure in the knowledge that they’ll work pretty much the same every time. To get them to work faster, take them on an empty stomach, but they’ll actually be stronger if you take them an hour after eating (this may change the effects, though).

It turned out that the two tablespoons of oil was exactly enough to saturate the 4 grams of ground cannabis I was using, so with those quantities, it would have been almost impossible to make it any stronger (and #00 capsules are about the largest most people can comfortably swallow in the first place).

When I filtered my oil, I put it into a calibrated shot glass to measure it, and it’s a good thing I did, because I found I had lost 15 ml of oil to the filter paper and absorption by the plant particles. I added another tablespoon of oil to get back to the proper dosage, otherwise I would have ended up with 20 very strong capsules! Next time I will start with three tablespoons of oil to compensate, which would allow more cannabis to be used if desired.

Tips and Tricks

So if you want to make your capsules much stronger than this, you’d have to use concentrated cannabis to begin with, i.e. hash (same idea: grind it up and heat it with the oil). Another trick for extra strength is to use less oil than would saturate the cannabis, add water to raise the liquid level to where it is all saturated, then boil until the water is gone (when it stops boiling on the same heat setting).

Lecithin Granules Make Edibles Work Better

Finally, the newest “hack” I’ve been using is to add lecithin granules to my oil mixes. Lecithin has a number of interesting properties, but in general it helps your body absorb and process fats more efficiently. I’ve generally seen an increased effect of 20% to 33% or so. I use a tablespoon of lecithin granules when making capsules, or up to four to six tablespoons for a full cup of cannabis cooking oil. It takes the granules awhile to melt, so I throw them in at the beginning while my crock-pot heats up, and when the granules disappear I know it’s up to working temperature. Then I add the cannabis and start the timer.

(Note: I no longer recommend adding lecithin due to a study that claimed it could cause heart damage — OH)

If you’re as sensitive as I am (I still get high off any more than 2 hits on my MFLB), the quantities I used will probably be a good start for your own experiments, but lots of people have higher tolerance. I actually used some AVB in this mix, because I had some. So using all buds will make it stronger; using 3 tablespoons of oil and 50% more buds will make it stronger still; grinding it to powder will let you get even more in; and after that there’s hash :-)

There are a lot of variations on cannabis capsules; here’s a very detailed article with two other methods of making them. Both these methods involve leaving the original plant material in the mix. This may make it stronger, and will also increase the theoretical healing effect, since everything will be going into your body. However, it will also make it harder to fill the capsules, since particles don’t always go through a syringe easily, and there will be less room for the oil itself.

Also, even finely-ground plant matter is hard to digest for some people; it may cause stomach upset or nausea. One last point is that I don’t advise heating your cannabis in an ordinary oven much higher than 300°F at any time (as both those methods in the link do) if you don’t want to risk losing THC.