Here is a tip for removing blood stains from carpet that some people might be unaware of. My veterinarian actually told me about this when my dog cut her leg on glass. Use inexpensive hydrogen peroxide to remove the blood. I use a small squirt bottle to apply it just where it's needed. It's amazing how this simple solution just dissolves the blood immediately. However, be careful as this could "bleach" out colors. By Mary (03/21/2005)
Use hydrogen peroxide.. pour a small amount and let it soak for about 5 mins., Blot then clean as usual (03/22/2005)
RE: Removing Blood from Carpet
Pour on a little Club Soda and let soak for a minute or two, then blot it up with a wad of kleenex. Do not rub - the kleenex will absorb much better than paper towels or cloth. Repeat if necessary. (03/23/2005)
You might try using a product called "Incredible". I buy it at my local Kroger grocery store in Houston, TX USA. I'd check at your local grocery store. You should be able to buy it at Walmart, Target, etc. too.
This stuff really is incredible. I've never had a stain that it didn't get out of carpet; it was a practically white wall to wall carpeting. It got out eye pencil makeup and plenty of other things I thought never would come out. Especially good as I was renting this particular condo, so I was panic stricken that I would be charged to replace wall to wall carpet or to pay a professional to get stains out. Good luck. (10/06/2009)
Peroxide normally works once the blood is dried. But I would probably test in on the carpet in a spot that isn't seen, just in case. I've never seen it change the color of clothing or anything, but carpet is probably different. (04/10/2010)
I would buy any of the number of enzymatic pet stain removers which work on all of the things pets could possibly to to a carpet. The enzymes work on the stain to remove it. If you can't find one let me know. I will send you link to several of them.
I had dried human blood drops all over the carpet. At least 100 drops. You will need container of diluted dishsoap water solution (maybe a half teaspoon soap for 3 cups water), water sprayer, and small wet/dry vacuum. With the solution, wet down stain thoroughly with water sprayer bottle. About 30 seconds to a minute later, dip a half paper towel into the soapy water, squeeze about 2 tablespoons soapy water onto the blood drop. Let set for about a minute. Massage into carpet with fingers for about 15-30 seconds. Add about 10 spays of water. Massage again for about 10 seconds. Vacuum up. That's it. Since I had so many, I finally discovered that this formula did it on most drops. Adding the water at the end provides additional liquid for the blood to flow through into the vacuum. For big drops, maybe a little more massage work. Honestly, I was quite surprised that this worked so well. (07/17/2010)