A poultice is a soft, moist paste made from herbs, clays, salts, or other materials that you spread onto skin (or wrap in cloth and press against skin) to treat localized pain, swelling, or infection. Sometimes called a cataplasm, it’s one of the oldest topical remedies in medicine, and versions of it are still used today for everything from boils to sore joints. The basic idea is simple: a poultice delivers moisture, heat or cold, and active ingredients directly to a specific spot on the body.
How a Poultice Works
Poultices rely on a few physical and biological mechanisms working together. The moist base keeps the skin soft and permeable, allowing active compounds from herbs or other ingredients to absorb more easily. When applied warm, a poultice dilates blood vessels in the area, increasing blood flow and encouraging the body’s natural inflammatory response to do its job faster. That extra circulation brings more immune cells to the site and helps clear away debris.
The “drawing” effect that poultices are famous for, especially for splinters and abscesses, comes from osmosis. Certain poultice materials like sugar, Epsom salt, and clay are osmotic, meaning they pull fluid toward themselves through tissue. A warm poultice applied over an abscess softens the overlying skin while drawing pus toward the surface, encouraging it to open and drain on its own. This is why Epsom salt poultices remain a common home treatment for boils.
Common Ingredients and What They’re Used For
Poultices can be made from a wide range of materials. The ingredient you choose depends on what you’re trying to treat.
- Clay or mud: Used for infections and drawing. Researchers have found that a poultice made from a specific type of blue clay (OMT Blue Clay) can fight certain disease-causing bacteria on wounds, including some antibiotic-resistant strains.
- Epsom salt: Mixed into a paste for abscesses and boils. The salt draws moisture and pus out of the swollen area, helping the boil drain.
- Ginger: Applied warm for joint pain and stiffness. A small study of 10 adults with osteoarthritis found that warm ginger compresses improved pain, stiffness, and overall well-being.
- Linseed (flaxseed): Traditionally used to soften hardened skin like calluses before treatment.
- Mustard: A classic chest and muscle poultice. When ground mustard contacts water, enzymes break down compounds in the seed into isothiocyanates, which irritate sensory nerve endings and dilate blood vessels near the surface. This creates a strong warming sensation and increases blood flow to the area.
- Activated charcoal: Sometimes used as a drawing agent for insect bites and minor skin infections.
Poultice vs. Compress
People often use these terms interchangeably, but they’re slightly different. A poultice is a paste or moist material, sometimes placed inside a cloth pouch, applied directly to the skin. It can be heated or left cold depending on the purpose. A compress, by contrast, is a cloth soaked in an herbal solution or medicated water, wrung out, and laid over the skin. The key difference is consistency: a poultice has body to it (think thick paste), while a compress is just a wet cloth. In practice, both deliver moisture and active ingredients topically, but poultices tend to hold heat longer and maintain contact with the skin more effectively.
How to Make and Apply One
The basic process is straightforward. Mix your chosen ingredient with enough water, coconut oil, or another liquid to form a spreadable paste. If you’re using dried herbs, crushing or grinding them first helps release their active compounds. Spread the paste about a quarter-inch thick onto a piece of clean cloth (muslin, gauze, or cotton work well), fold the cloth over the paste, and place it against the skin with the thinner side down so the ingredients can make contact.
For a warm poultice, heat the paste gently before applying, or warm the assembled poultice briefly. Test the temperature on the inside of your wrist first. Secure it with a bandage or additional cloth to keep it in place. Most poultices are left on for 20 minutes to several hours depending on the ingredient and purpose, though some need much shorter application times.
What the Research Shows
Scientific evidence on poultices is still limited compared to conventional treatments, but some findings are promising. In an animal study published through the National Institutes of Health, a poultice containing fulvic acid (a compound found in soil and decomposed organic matter) was applied daily to full-thickness skin wounds on rats. By the end of week four, wounds in the poultice group had completely closed, while those in the control groups had not. Under a microscope, the poultice-treated tissue showed fewer inflammatory cells and more of the fibroblasts and blood vessels needed for healthy healing.
A 2016 animal study also found that a poultice made from a tropical fern showed potential for treating diabetic ulcers, though human trials are still needed for most of these applications. The evidence is strongest for the basic physical mechanisms: warmth increases blood flow, osmotic materials draw fluid, and moisture softens tissue. These aren’t controversial claims; they’re well-understood physics applied to the body.
Safety Risks to Know About
Poultices are generally mild, but a few ingredients carry real risks. Mustard is the most important one to get right. Because mustard’s active compounds chemically irritate the skin, leaving a mustard poultice on too long causes burns. Adults should limit application to 10 to 15 minutes, and children to 5 to 10 minutes. Leaving one on for 15 to 30 minutes can cause severe burns, especially on sensitive skin.
Garlic is another ingredient that demands caution. A published case report describes a significant chemical burn on a patient’s face after applying a raw garlic poultice for toothache. Garlic contains compounds that are caustic to skin, particularly when left in direct contact for extended periods. If you’re using garlic in a poultice, dilute it well and limit contact time.
More broadly, any poultice ingredient can cause contact irritation or an allergic reaction. Test a small amount on a patch of skin before applying it to a larger or more sensitive area. Never apply a poultice to broken or deeply infected skin without understanding what you’re putting on it, as some materials can trap bacteria or introduce contaminants into an open wound.