I've had very good success using both salt and baking soda for brown recluse bites. I live in Missouri and have been bitten three times. With this most recent bite, I immediately washed with soap and water when I realized what had woken me up, dried, and applied salt. I wet a bandage with witch hazel, generously applied a layer of salt, and taped it over the bite.
When removing the salt 2 hours later, I could see a moistened area right over the puncture site, which I really believe to be some of the venom being drawn out.
I then applied a dab of Neopsorin and spent most of that day and the next icing for 15 minutes at a time, reapplying salt a couple of times. Ice is a must for the swelling and pain and/or intense itching. I once read it can actually help neutralize some of the venom; I'm not sure if this is true but it certainly feels much better.
I've likewise read that heat can exacerbate the bite and believe that to be true based on experience. For the next couple of days I took a bath as cool as I could comfortably stand, with a bit of Epsom salts and baking soda, and believe it helped a lot. I also increased my vitamin C the first few days, 3,000 mg daily (I probably could have gone higher), and turmeric 1,500 mg daily.
About a week later, the bite is healing beautifully, and I don't believe it will leave a scar at all. I'm at this point just applying Neosporin and a Band-Aid at night. I've had similar great results using baking soda in a similar way, again seeing a moist spot in the baking soda after a couple of hours. (I just didn't immediately have baking soda on hand this time around so used plain salt instead.)
The only bite that did take a very long time to heal and has left a noticeable scar is the one where I never applied baking soda or salt (Not realizing until later that a brown recluse bite is actually what it was). ~