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8 Benefits of Aloe Vera + Side Effects

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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Aloe vera has long been used as a household cure for many ailments. Its anti-inflammatory and antimicrobial activities make topical aloe vera especially valued for wounds, open sores, and skincare. By mouth, it may protect against diabetes, improve constipation, and ease heartburn. Read on to learn more about the potential uses and side effects of aloe vera.

What Is Aloe Vera?

Aloe vera (Aloe barbadensis miller) is a shrubby green plant. It grows in the dry regions of America, Africa, Asia, and Europe. Many people have used aloe for its beauty, health, and medicinal effects for centuries [1].

Forms of Aloe Vera

  • Gel: aloe vera gel can be applied onto the skin to help reduce inflammation, clear skin, and heal wounds [2].
  • Juice and Supplements (capsules): aloe vera can be taken orally via supplements or juice to stop constipation, boost the immune system, or reduce diabetes symptoms [1].

Constituents

Aloe vera leaves have three layers [1, 3, 4]:

  • Rind (outer layer) – It protects the plant, transports substances (water and starch), and produces proteins and carbs.
  • Latex (middle) – It contains glycosides (sugars bound to another compound) and anthraquinones (phenolic compounds). Barbaloin/aloin, isobarbaloin, and emodin are the main active compounds.
  • Gel (inside) – It contains water, sugar, amino acids, fat, and vitamins. Glucomannan, salicylic acid, and phytosterols are the main active compounds.

The latex and gel contain most of its active compounds. Aloe vera’s vitamins and anthraquinones have antioxidant properties. Its enzymes, glycoproteins, fatty acids, and hormones are anti-inflammatory [1].

Snapshot

Proponents

  • May help with wounds, sores, and skin dryness or inflammation
  • May lower blood sugar and fat levels in diabetics
  • Anti-inflammatory and antimicrobial activity
  • May help with constipation and heartburn
  • Relatively safe when applied on the skin

Skeptics

  • Insufficient evidence for some benefits
  • Normal oral doses may cause digestive issues
  • Prolonged use may cause electrolyte deficit leading to heart problems
  • Serious adverse effects reported from high oral doses
  • Oral aloe vera is not safe for pregnant women and children
  • Potential interaction with blood thinners

Health Benefits

Possibly Effective for:

1) Wounds

In 3 studies of 80 burn patients, aloe vera gel helped treat burn wounds better than two antibacterial ointments (nitrofurazone and silver sulphadiazine). The aloe gel helped regrow new skin faster and relieved pain better than the ointments. Aloe gel was also effective in 12 burn patients who underwent split-thickness skin grafts [5, 6, 7, 8].

In another study of 18 facial scarring patients, topical aloe vera gel helped heal skin more quickly. The treatment also reduced pain from their wounds better than antibacterial ointment. Similarly, aloe vera juice powder improved wound healing, pain, and bleeding in a trial on 60 people with anal fissures [9, 10].

Aloe vera gel also helped with chronic wounds in 2 trials on 137 people. It was at least as effective as two gels (phenytoin and betamethasone) [11, 12].

Aloe vera also sped up the healing of surgical wounds. It was effective in 2 clinical trials on 80 women who underwent a cesarean section and 49 people recovering from hemorrhoid removal [13, 14].

However, there are conflicting results from other studies. In a trial on 21 women with surgical scars, applying aloe vera gel on their skin significantly delayed wound healing compared to a standard ointment [15].

Aloe vera’s constituents, glucomannan (sugar) and gibberellin (a plant growth hormone), interact with growth factors, which may stimulate skin cell activity and growth. This is how topical and oral aloe vera may stimulate collagen formation and heal wounds [1].

Additionally, aloe vera improved collagen composition, which helps heal wounds faster [16].

All in all, the evidence suggests that aloe vera may speed up wound healing. You may discuss with your doctor if it may be helpful in your case.

2) Skin Health

In a study of 30 participants with dry hands, aloe vera gel (by wearing a glove for 8 hours a day) improved dry skin after about 4 days. There was a significant improvement after 10 days in skin strength, wrinkling, and reddening. Similarly, topical aloe vera moisturized the forearm skin of 20 female volunteers [17, 18].

In a study of 41 psoriasis patients, aloe vera gel decreased redness, peeling, and pain by 72.5%. However, the placebo was more effective at reducing psoriasis symptoms (82.5%). Another aloe vera gel was more effective than a topical corticosteroid (triamcinolone acetonide) in a clinical trial on 80 people with mild to moderate psoriasis [19, 20].

Similarly, a gel with aloe vera among other ingredients was effective at improving mild to moderate seborrheic dermatitis in a small trial on 25 people [21].

Aloe vera gel application on rat skin increased the formation of metallothionein, an antioxidant protein. The protein stops UV ray-caused oxidative damage, prevents antioxidant suppression, and reduced immunosuppressive cytokine (IL-10) release [22].

Sugars from aloe vera may help moisturize the skin by stimulating skin cells. The increase in collagen and elastin may soften the skin, make it more elastic, and reduce wrinkles [17, 1].

Although limited, the evidence suggests that aloe vera may help moisturize, improve inflammatory conditions, and reduce oxidative damage in the skin. Discuss with your doctor if it may help you as a complementary strategy in your case.

3) Diabetes

In a clinical trial on 30 type 2 diabetic patients (with high cholesterol), aloe gel capsule supplementation helped control diabetes. Taking 300 mg of aloe gel capsules twice daily for two months lowered blood sugar, total cholesterol, and LDL (bad cholesterol) levels. It also lowered HBA1c, a long-term measure of blood sugar [23].

Similarly, two aloe vera leaf gel products lowered blood sugar, insulin, and cholesterol (total and LDL cholesterol) in a clinical trial on 45 people at risk of type 2 diabetes. In another trial on 136 obese prediabetic people, an aloe vera gel complex reduced body weight and insulin resistance [24, 25].

A meta-analysis of 9 studies found that diabetic patients had the most improvement in blood sugar after taking aloe compared to healthy patients [26].

In human cells, an aloe vera compound (aloe-emodin glycosides) increased glucose uptake and glycogen synthesis. This may reduce glucose levels and help stop insulin resistance [27].

Again, limited evidence suggests that oral aloe vera may help lower blood sugar and fat levels in people with type 2 diabetes. You may consult with your doctor if aloe vera is recommended in your case. Importantly, never take aloe vera in place of the antidiabetic medication prescribed by your doctor.

Insufficient Evidence for:

1) Mouth Sores

In a study of 40 patients with canker sores (minor aphthous lesions), aloe vera gel decreased healing time. It reduced pain and wound size [28].

In another study of 90 patients, aloe vera gel fully healed 76% of the patients’ canker sores. It was especially efficient at decreasing ulcer size, redness, and oozing [29].

In a clinical trial on 26 neck-and-cancer patients, a mouthwash with aloe vera was as effective as the anti-inflammatory benzydamine at relieving mouth sores caused by radiotherapy. However, another trial on 58 people found aloe vera gel ineffective. This may be due to a low cumulative radiation level, since aloe gel (added to mild soap) was only effective at high doses in another trial [30, 31, 32].

To sum up, the results concerning canker sores are promising but limited while those on radiotherapy sores are mixed. There is insufficient evidence to support this use of aloe vera until further clinical research is conducted.

2) Anti-Inflammatory

In a study of 40 volunteers, topical aloe vera gel reduced UV-ray induced inflammation when applied on their backs. Aloe vera gel was better at reducing inflammation and redness than hydrocortisone cream [33].

In mice, its application on the ears reduced inflammation caused by an irritant [34].

In human colon cells, aloe vera gel dose-dependently inhibited inflammation. This suggests that aloe vera has potential in treating inflammatory bowel disease [35].

Aloe vera gel also suppressed inflammatory markers in human immune cells [36].

Aloe vera’s anti-inflammatory effects come from its ability to reduce PGE2 production and stop the cyclooxygenase pathway [1].

Aloe vera also suppresses other inflammatory markers like TNF-a and IL-1B [37].

It contains C-glucosyl chrome, an anti-inflammatory compound [38].

Although promising, the evidence is insufficient to claim that aloe vera helps with inflammatory conditions. More clinical research is needed to establish how to use it therapeutically.

3) Antimicrobial

In a clinical trial on 390 people, aloe vera mouthwash was as effective as antibacterial chemicals in removing plaque. After 30 days, the aloe vera group also had healthier gums and less plaque compared to the controls [39].

Herpes simplex is a virus that can cause cold sores and other diseases in the mouth. Aloe vera gel killed herpes simplex virus without being toxic to other cells [40].

Aloin (extracted from aloe vera) inactivated several viruses (influenza, herpes simplex, and varicella zoster) [41].

Water and alcohol aloe vera extracts inhibited gram-positive and gram-negative bacteria, although the alcoholic extract was more efficient. The extracts inhibited Enterococcus bovis, Staphylococcus aureus, E. coli, Proteus vulgaris, P. mirabilis, Pseudomonas aeruginosa, Morganella morganii, and Klebsiella pneumoniae in test tubes [42].

Purified aloe vera protein also inhibited fungal growth (Candida paraprilosis, C. krusei, and C. albicans) [43].

Aloe vera contains antimicrobial compounds (phenols, sulfur, salicylic acid, lupeol, urea nitrogen, and cinnamic acid), which inhibit viruses, bacteria, and fungi [1].

Aloe vera breaks bacterial cells to stop their growth [44].

Although the results are promising, a single clinical trial and a few cell-based studies cannot be considered sufficient evidence to back the use of aloe vera against infectious diseases. More clinical trials on infected people are needed to confirm these preliminary results.

4) Constipation

Aloe vera may help relieve constipation. In a study of 35 chronically constipated patients, aloe vera and fiber pills helped reduce constipation more than the control pills. The patients experienced more frequent bowel movements, softer stools, and took laxatives less often [45].

In rats, aloe-emodin extracted from aloe vera had such a strong laxative effect that it even induced diarrhea [46].

Phenolic compounds from aloe vera latex are responsible for its laxative effects. They stimulate the intestine, increase intestinal water, and stimulates contractions (peristalsis) [46].

A small clinical trial and some animal and cell research are clearly insufficient to support this use. Larger, more robust human studies are needed to validate these preliminary findings.

Importantly, because the safety of oral aloe vera was not well established, the FDA demanded that over-the-counter laxatives with aloe vera be either reformulated or removed from the market in 2002.

5) Heartburn

In a pilot study of 79 acid reflux patients, aloe vera was effective in relieving heartburn and acid reflux symptoms. Compared to the group who received Omeprazole (a commonly prescribed heartburn medicine), the aloe vera group also had reduced heartburn, gas, vomiting, nausea, gas, and other symptoms. Aloe vera was well tolerated and had few adverse effects [47].

A single clinical trial is insufficient to claim that aloe vera helps with heartburn. Further clinical research is needed to confirm its results and evaluate aloe vera’s safety when used for this purpose.

Animal and Cell Research (Lack of Evidence)

Immunity Boost

No clinical evidence supports the use of aloe vera for an immunity boost. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

Aloe vera contains many antioxidants – Vitamin C and E, flavonoids, tannins, and carotenoids. By stopping oxidative damage, the antioxidants can protect the immune system [48].

In guinea pigs, alprogen (an aloe vera constituent), inhibited mast cell formation. Mast cells are white blood cells that may cause inflammation and hypersensitivity or allergic reactions. When alprogen inhibited mast cell formation, it prevented histamine and leukotriene release and prevented allergic reactions [49].

Aloe vera extract also caused mice white blood cells to release interleukin-1 and tumor necrosis factor, which stimulates the immune system [50].

Aloeride, a sugar from aloe vera juice, activated white blood cells (macrophages), which also stimulates immune system function [51].

Limitation & Caveats

Aside from its topical application and oral intake for diabetes, the rest of the potential benefits have been insufficiently investigated. Further clinical research is needed to confirm the preliminary results on other potential uses of aloe vera.

Side Effects & Precautions

This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects.

Call your doctor for medical advice about side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.

Common side effects of topical aloe vera include [4]:

  • Skin rashes
  • Burning and stinging

When taken by mouth, aloe vera has been reported to cause [4]:

  • Diarrhea
  • Vomiting
  • Stomach cramps
  • Constipation (in rare cases)

Most of these effects can cause electrolyte imbalance, especially if used for a long time. Electrolyte deficiency (especially potassium deficiency) due to prolonged aloe vera use may cause irregular heart rate and increase the risk of heart failure [52].

In various case studies, high oral doses of aloe vera caused kidney failure, hepatitis, liver dysfunction, and even hyperthyroidism [4].

High doses of aloe vera decreased brain activity in mice. After 90 days, it also damaged sperm, decreased red blood cell count, and increased cell death [53].

Two years of aloe vera leaf extract administration in drinking water caused rats to develop tumors in their intestines. Aloin has been identified as the compound responsible for causing colorectal cancer [54].

Contraindications

People who are allergic to Liliaceae plants (onions, garlic, tulips, etc.) should avoid using aloe vera [52].

Pregnant women are also advised to not take aloe vera. It can have toxic effects on their embryo and fetus. It may also cause contractions [4, 1].

Due to the lack of safety data, children should also avoid oral aloe vera.

People with heart or kidney problems should be careful taking aloe vera as it can create an imbalance in the body’s electrolytes and cause potassium deficiency [4].

Drug Interactions

Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.

Aloe vera may have antiplatelet activity, meaning that it can cause blood thinning. In one case, a woman taking aloe vera supplements experienced severe bleeding after oral surgery. Aloe vera interacted with sevoflurane to increase bleeding. However, no other studies have shown these effects [55].

Gene Interactions

Aloe vera gel increased the production of GLUT-4, a protein needed to get glucose into cells, in mice [56, 57].

Processed aloe vera gel reduced the production of SREBP-1a, FAS, and GPAT in mice. These genes are known to have an effect on fat synthesis [4].

Sugars from aloe vera gel induced MMP-3 and TIMP-2 production in rats. This may help with wound repair and collagen formation [58].

Supplementation

Dosages

Because aloe vera is not approved by the FDA for any condition, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if aloe vera may be useful as a complementary approach in your case and which dose you should take.

Topically, aloe vera can be applied liberally on the skin to prevent dryness, soften skin, and reduce wrinkles [52].

When using to treat constipation, 0.04-0.17 grams of dried aloe vera juice is recommended. Additionally, a combination of 150 mg dried juice, psyllium (50 mg), and celandine (300 mg) seems to be a safe alternative [52].

People normally drink 5-15 mL of aloe vera juice twice daily to help with diabetes [52].

Aloe vera injection is not recommended [52].

User Reviews

Most users applied aloe vera on the skin to improve wounds, sunburns, and open sores. They often reported satisfactory results.

However, not all users were satisfied. One with open sores complained that aloe improved wound healing but had no effect on pain.

People with sensitive skin used aloe vera for skincare and normally reported good results.

A few users took in oral aloe vera for digestive issues, also reporting good results in general. However, some of them complained about digestive issues such as diarrhea, nausea, and cramping.

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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