Bentonite clay is formed from aged volcanic ashes and is most often used to detox and to cleanse skin and hair. Read on to learn more about this healing clay’s components, how it works, and when to use caution.
What Is Bentonite Clay?
Bentonite clay tops the list of healing clays, many of which have been used for enhancing health since ancient times .
Bentonite clay forms when volcanic ashes react with sea water and take up its minerals. This clay has no taste or smell and its color can vary from light (cream, yellow, green) to darker (brown, black) tones depending on its impurities. Its consistency is very soft and it doesn’t stain [2, 3].
Bentonite clay is named after its largest source in the world (Fort Benton, Wyoming). The name of its main component, montmorillonite, derives from the place where it was first discovered (Montmorillon, France). The US is the largest producer, followed by China, Greece, and India .
You may be surprised to know that humans have been using clays both internally and externally throughout history. Scientists think that “geophagy” or earth-eating was an adaptive behavior for acquiring nutrients from soil and eliminating gut parasites and toxins [1, 5, 6].
Bentonite and other clays have traditionally been eaten and applied on the skin and hair for [7, 1]:
- Nutrient deficiencies
- Diarrhea and other digestive issues
- Skin irritation
- Hair cleansing and softening
What makes bentonite clay different from similar clays, such as kaolin clay? Let’s take a look.
Kaolin Clay vs Bentonite Clay
Kaolin is a clay with a similar composition to bentonite. But kaolin has a different chemical structure, which reduces its capacity to retain water and electrolytes [8, 9].
Both clays are common ingredients of face masks but have different effects. Since bentonite is a better absorbent, it can remove more fat and toxins from the skin. In turn, kaolin is more efficient at exfoliating dead skin due to its larger particles .
People with oily skin would do better with bentonite masks, while those with drier, more sensitive skin should choose kaolin.
Aside from these two clays, Fuller’s earth is another option for skin care. Research suggests it absorbs toxins and reduces the detrimental effects of pollution on the skin .
Components & How It Works
The main component is montmorillonite, a soft clay formed by layers of silica and alumina. Montmorillonite is normally bound to many clay minerals, especially sodium, calcium, magnesium, and aluminum [8, 3].
Bentonite may also contain small amounts of impurities such as other clays (illite, kaolinite) and crystalline silica (quartz, cristobalite). While the levels typically found in this clay are not dangerous, both kaolin and crystalline silica dust may cause lung diseases if breathed in large amounts. Silica dust is also linked to autoimmune disorders, kidney damage, and cancer [8, 3].
Montmorillonite’s negative charge gives rise to bentonite clay’s effects. Similar to a magnet, it attracts positively charged molecules and binds them to its surface (adsorbs them). This way, it can trap many heavy metals and toxins, preventing them from entering the body [12, 9].
Montmorillonite particles have an astonishingly large surface area, which gives them a high capacity to bind toxins. The particles also take up water alongside toxins, infusing both into the spaces between their layers and causing the whole clay to swell .
Drug Delivery Systems
Bentonite clay can be modified into synthetic materials (with polymers). These can be used as improved delivery and slow-release systems of drugs for :
- Cancer (such as doxorubicin, paclitaxel, and tamoxifen) [14, 15, 16, 17, 18, 19, 20, 21, 22]
- Infections (ciprofloxacin, curcumin, praziquantel) [23, 24, 25]
- Sunscreen protection (Eusolex, NeoHeliopan, zinc and titanium oxides) [26, 27]
- Glaucoma (betaxolol) 
- Psychiatric disorders (olanzapine) 
- Impotence (sildenafil) 
In the case of sildenafil, bentonite clay also helped mask its unpleasant taste .
How to Use Bentonite Clay
Bentonite clay normally comes as a clay powder. You can prepare a paste simply by adding water until you achieve the desired, yogurt-like consistency. To make sure your clay is not too diluted, add water to the powder bit by bit, letting the clay soak it up gradually.
Note: Bentonite clay might react with metal objects and lose effectiveness, although studies are lacking to confirm this claim. To stay on the safe side, consumers and manufacturers often recommend using ceramic or glass bowls and plastic or wooden spoons.
You can experiment with bentonite clay powder for external use at home almost endlessly. Here are some ideas:
- Soothing skin paste: apply a paste on burns, bites, and rashes, and leave until it dries.
- Face mask: make a paste and leave on the skin for 10-20 minutes.
- Hair mask: apply a paste on the hair from root to tip 1x-2x/week. You can add a bit of apple cider vinegar with water and even mix in a couple of drops of your favorite hair-nourishing oil.
- Armpit detox: apply a paste on the armpits to remove toxins.
- Skin-softening bath: add bentonite clay to your bath water to soften the skin and get rid of built-up skin toxins.
- Homemade soap: this is slightly more complicated, but you can combine bentonite clay with oils and lye to make soap for oily skin.
- Tooth-brushing powder: clean your teeth with bentonite clay to remineralize them, make them whiter, and kill bacteria.
If you prefer, you can buy ready-to-use bentonite clay versions of most of these DIY remedies.
The FDA hasn’t approved bentonite clay for any topical uses. Before using this clay (or any natural remedies) on the skin, do a skin test for allergies. Apply a small amount, wait for 24 hours, and continue using the product if you don’t experience any reactions.
You can also take bentonite clay by mouth to remove toxins and help digestion. Bentonite clay has the FDA generally recognized as safe (GRAS) status as a food ingredient but is not approved for any conditions.
Users and manufacturers have established unofficial doses. As a rule of thumb, dissolve 0.5-1 teaspoon bentonite clay in 1 cup of water and drink 1x/day. Most clinical trials used up to 3g/day. In this case, you want to be absolutely certain that you have food-grade clay. Bentonite clay supplements are also available in tablets and capsules.
Finally, you can mix bentonite clay with water and give it to your pets to improve digestive issues or poisoning. The dose will depend on the size of the animal. However, we recommend consulting your veterinarian before giving your pets bentonite clay.
Side Effects & Cautions
Bentonite clay (1.5-3 g/day) is relatively safe and only caused mild digestive symptoms (flatulence, stomach pain, bloating, constipation, diarrhea) in less than 10% of people taking it for 2 weeks. Half this dose didn’t cause any adverse effects in children. In both adults and children, it didn’t reduce the uptake of minerals and vitamins [31, 32, 33].
In contrast, excessive oral doses may cause nutrient deficits. A 3-year-old girl who was given adult doses and a cat that ate litter containing this clay developed severe potassium deficit with vomiting, constipation, sleepiness, and weakness [34, 35].
Similarly, topical bentonite clay was generally safe in clinical trials. Only one person developed mild, temporary skin redness from a bentonite clay lotion .
High exposure to bentonite clay dust from mines and steel plants was associated with an increased incidence of respiratory diseases and cell damage in several studies. However, its potentially toxic impurities (quartz, kaolin, perlite) could have contributed to these effects [37, 38, 39, 40].
A dental assistant had a severe corneal inflammation with reduced vision and sensitivity to light after a tooth-polishing paste with bentonite clay came in contact with her eye .
Although its use during pregnancy or breastfeeding is not investigated in women, bentonite clay didn’t reduce mineral uptake or utilization in pregnant rats .
Bentonite clay may bind to some drugs, especially those positively charged, and prevent their transport into the bloodstream. Some of these drugs include:
- Antibiotics (such as tetracycline, trimethoprim, and rifampicin) [43, 44, 45, 46, 47, 48, 49]
- Drugs for heart disease (digoxin, quinidine) [50, 51]
- Antiallergic drugs (promethazine, chlorpheniramine) [52, 53]
- Stimulants (caffeine, amphetamine) [54, 55]
- Drugs for psychiatric disorders (lithium) 
- Drugs for respiratory diseases (theophylline) 
- Sedatives (propoxyphene) 
- Antidiabetic drugs (metformin) 
Consult your doctor before using bentonite clay internally if you take medication.
Best Bentonite Clay
There are two main types of bentonite clay: sodium and calcium :
- Sodium bentonite clay absorbs more water. While this makes it more effective at removing toxins, the clay is very alkaline and can be too aggressive to the skin. By mouth, it may cause constipation.
- Calcium bentonite clay takes up more electrolytes, making it more effective in case of poisoning. This clay is less alkaline and absorbs less water than sodium bentonite.
Although it’s generally assumed that only calcium bentonite can be used internally, both types are safe if they come from reputable sources. It’s important to buy pure/clean bentonite with a high montmorillonite content and free of toxic contaminants.
For instance, the FDA issued warnings against two bentonite clay masks (Bentonite Me Baby and Best Bentonite Clay) after laboratory tests found unsafe levels of lead.
If you are planning to take it by mouth, make sure it’s food-grade bentonite clay. The one for external use may contain additives that shouldn’t be ingested.
Bentonite clay normally comes as a clay powder you can mix with water. It’s easy to make a paste and use it as a skin-soothing ointment, face and hair mask, or armpit detox. Plus, you can add it to your bath water or brush your teeth with the powder. Ready-to-use skincare products with the clay are also available.
You can also prepare a detox drink with food-grade bentonite clay. Capsules or tablets are another option for oral use. Be sure to consult your doctor if you take medication (as bentonite clay can bind to it) or are pregnant before using it internally.