I've been on this for the past 8 months, I'll give my my observations and assessments. THIS PERTAINS ONLY TO TRACTOR SUPPLY.
First - I went to my local Tractor Supply yesterday ( Friday 10/22/2021 ) - and they were fully-stocked on ivermectin products again. There was at least one new brand I'd never seen before, which was three times as expensive as everything else.
Second, you don't want to get any that contain other drugs.
There are two oral pastes - Durvet and Med-Pharmex. Both are "Apple Flavor." The Durvet 0.21 oz paste was $6.99 per tube, which is 3-6 doses depending on your weight. The Med-Pharmex has a box of 6 tubes for $21.99.
The "Pour On" from Durvet comes in a big yellow and red box. I looked-up the ingredients listed on their site, and all are used in human creams as well. The pour-on appears to be the cheapest way to get ivermectin. As noted before, all you do is withdraw 1-5 ml, and rub them into your skin somewhere. I used my ankles as a test, and had no adverse reaction.
The "pour on" apparently acts the same way as oral application, with the same dosages.
There is also Durvet injectable ivermectin. This can also be taken orally as well, apparently. But - it seems pretty expensive relative to the other forms. If you inject it, please use proper technique.
Protocols can be found here: https://covid19criticalcare.com/ .
I suggest you get a syringe to measure how much you apply.
I have been using the above for about six months now. I have noticed no bad side-effects. I cannot say that I've noticed any "good" side-effects, either.
Earl