The term poultice comes from the Latin word for porridge. It was not uncommon to treat inflammations with porridge spread on a cloth and then applied to the inflamed area. They might also cover the chest during a chest cold. Usually, however, plain porridge mixed with mustard was applied directly on the chest and was called a plaster. Poultices may also be called cataplasms.
Whatever the ingredients for a poultice, it is always a wet substance applied to inflammation or sore spots. Its most common use today is in horses, instead of people. People tend to either ice swelling to reduce it, or heat areas with heating pads. The closest thing to a cataplasm for humans is probably the application of a hot washcloth to large pimples or abscesses to make them form a head and then drain. This is also good for areas that have ingrown hairs. Here, the only wet ingredient is usually water, though some add peroxide as well.
In horses and other farm animals, the most common usage of the poultice is its application to reduce swelling of the joints. Some use a simple cool bran or oatmeal cereal, essentially porridge, on a cloth, and then cover the area with a bandage to secure the cloth. This treatment may be used on abscesses to help the abscess drain.
There are a few poultices that may use disinfectant or antibacterial agents, which are available for commercial sale. These can usually be obtained through a horse vet or a farm animal vet, or at local feed stores. Even though this method is old medicine, it still makes for good medicine in the field of veterinary science.
Veterinarians recommend that one should never use a poultice over an open wound. This makes sense for people using one, too. This may cause the wound to take longer to heal.
However, some surgical wounds that are not healing properly in humans are given a wet to dry dressing, similar to a poultice. The first layers of the dressing are gauze soaked in antibacterial medication. Several applications of the soaked layers are followed by layers of dry gauze and perhaps tape. This type of dressing should only be done under a doctor’s orders.