Apart from the beauty of their bright yellow-orange flowers, calendula may have health benefits that stem from their anti-inflammatory, antioxidant and anticancer properties. Learn more about their benefits and what side effects to watch out for.
What are Marigolds?
Marigold plants of the Calendula and Tagetes genera have different origins and somewhat distinctive qualities. Both are members of the sunflower family (Asteraceae) and bloom gorgeous colorful flowers. Some species of Marigolds are mainly used as decorative garden plants, while the flowers and leaves of other species have been nurtured as remedies in both European and Native American folk medicine [1, 2].
The Calendula genus is native to central Europe and the Mediterranean. It includes 25 species, the most common ones being English or pot marigold (Calendula officinalis) and field marigold (Calendula arvensis) .
Pot marigold or common marigold is also simply known as calendula. It has been used since the 12th century for its medicinal properties. Due to its triterpenoids and flavonoids, pot marigold is being investigated for antioxidant, anti-inflammatory, antibacterial, antiviral, and anticancer properties [3, 1, 4].
Field marigold has been used traditionally in Spanish and Italian folk medicine for fevers, reducing inflammation, and fighting cancer. People would crush the leaves and use them to close wounds while the flowers were applied to burns.
Animal and cell-based studies confirmed some of the traditional uses but also uncovered the antioxidant, antibacterial, antifungal, and antiviral properties of this herb [1, 5, 6].
Native American & Other Marigolds
The Tagetes plants include 56 species native to South America, and nowadays cultivated in Europe, Africa, and Asia. Traditionally, their ornamental flowers were used to make decorations and accompany ceremonies .
Thienyls from the roots of these plants have antifungal properties, whereas terpenoids from flowers and leaves have antibacterial and antioxidant properties. Aside from being bug repellants, they are used as remedies for dental, stomach, gut, and emotional problems .
Tagetes erecta, commonly known as Aztec marigold is native to Mexico. Historically, the Aztecs used this plant as a remedy for boils, injuries, headaches, earaches, stomach aches, and colds. Studies show that Aztec marigold also has antibacterial, antifungal, antioxidant, anticancer and antidepressant properties [8, 9, 2, 10].
Tagetes lucida, also known as Mexican marigold or Spanish Tarragon, is native to Mexico and Central America. It is used traditionally as an anti-inflammatory, but also to reduce anxiety, depression, and emotional issues. The Aztecs considered this plant a remedy for cancer, dementia, and fever, while its flowers are used for seasoning and coloring food [11, 12, 2, 13].
In Bangladesh, the leaves of French marigold (Tagetes patula) are applied to boils and calluses. The leaves are also used for kidney disease, muscle pain, and hemorrhoids, whereas their juice is applied to reduce eye infections. In Pakistan, both the leaves and flowers are used to lower fever. Extracts of French marigold have antibacterial, antifungal, antioxidant and anti-inflammatory properties [14, 2, 15, 16, 17].
Tagetes minuta or wild marigold is used widely in the folk medicine of Africa, Latin America, and Pakistan. Leaves and flower infusions are used as traditional remedies for wounds, sores, dental infections, skin conditions, cough, and stomach disorders, and insomnia. Extracts of the wild marigold can kill bacteria, fungi and repel insects [18, 19, 20, 21, 22, 23].
But do any of these traditional remedies have a scientific leg to stand on? Read on to find out.
Types of Marigolds
There are various types of marigolds, each with its own characteristics and properties [24, 12, 25, 2, 26].
The health benefits and risks of marigolds [27, 28, 29, 30, 31, 24, 12, 2, 26, 32, 33, 34, 35, 36, 37]:
- May promote skin health
- May accelerate wound healing
- May improve oral health
- Possible benefits for infections & menstrual cramps
- Easy to grow, harvest, and use
- Possible allergic reactions
- Possible drug interactions
- Likely unsafe for pregnant or breastfeeding women
The Calendula (officinalis, arvensis) plants contain [38, 24, 29, 39, 40, 32, 41, 3]:
- Flavonoids (quercetin, rutin, narcissin, isorhamnetin, kaempferol)
- Phenolic acids
- Carotenoids (beta-carotene)
- Triterpenoids (faradiol laurate, faradiol myristate, faradiol monoester)
- Fatty acids (calendic acid, linoleic acid, stearic acid)
- Complex sugars (polysaccharides)
- Minerals (potassium , sodium, magnesium, calcium, iron)
- Amino acids (alanine, arginine, lysine, tyrosine)
- Volatile oils
The Tagetes (erecta, lucida, patula, minuta) plants contain [42, 43, 27, 9, 44, 45, 2]:
- Minerals (iron, copper, magnesium, calcium, zinc)
- Phenolic acids
- Fatty acids
Potential Benefits of Calendula
Marigold supplements have not been approved by the FDA for medical use and generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Possibly Effective For
1) Skin Health
People with cancer who are treated with radiation can develop radiation dermatitis, a skin inflammation that causes skin redness, dryness, or peeling [46, 47].
In clinical studies of over 700 people undergoing radiation, pot marigold (Calendula officinalis) cream or oil decreased the risk of radiation dermatitis and reduced pain caused by radiation [48, 49, 50].
In 130 children with diaper rash (dermatitis), pot marigold ointment reduced the symptoms (rash, tissue damage) [51, 52].
However, in clinical trials of over 300 children, alternative treatments (Bentonite, olive oil cream, shampoo-clay) improved diaper rash symptoms faster and better than pot marigold ointment [53, 54, 55, 56].
Pot marigold ointment reduced tissue damage and improved a skin condition causing dry peeling lips (exfoliative cheilitis) in an 18-year old man .
Matrix metalloproteinases (MMPs) are enzymes that break down the components of the connective tissues and skin. Increased MMP-1 and MMP-2 production can cause skin damage, wrinkles, and skin aging. In cell studies, both Aztec marigold and pot marigold extracts reduced MMP-1 and MMP-2, while increasing collagen and laminin-5 [58, 59, 60, 61, 62, 62, 27, 63, 64].
Laminin-5 is a key skin protein. Increased laminin-5 production can rejuvenate the skin, prevent damage, and accelerate wound healing [65, 66, 67].
In another cell study, pot marigold essential oil reduced oxidative stress, prevented skin aging, and protected the skin from sunburns .
Marigolds also promote skin health by reducing swelling and preventing skin inflammation [27, 24, 28, 68, 48, 49].
2) Wound and Burn Healing
In clinical studies with more than 200 people with foot conditions that cause injuries or calluses (such as diabetic feet), pot marigold (Calendula officinalis), French marigold (Tagetes patula), and Aztec marigold (Tagetes erecta) extracts blocked infections, reduced the wounds and calluses sizes, diminished the pain, and decreased itching and redness [69, 70, 71, 72, 73, 74, 75].
In several clinical studies with over 150 people with chronic skin wounds (various ulcers or diabetic foot), pot marigold spray reduced the number of wounds, dead tissue, and bad smell, while speeding up healing [76, 77, 78].
In a clinical study on 156 people with burns, pot marigold ointment sped up the healing process better than just vaseline .
In 111 women who had vaginal wounds from a surgical procedure for easier childbirth (episiotomy), pot marigold ointment decreased swelling and increased the speed of healing .
In 24 women who had a cesarean section, field marigold (Calendula arvensis) oil together with St John’s wort oil improved surgical wounds better and faster than the placebo .
In animals (rats, mice), oral and topical application of pot marigold increased the collagen production, decreased oxidative stress, and speeded wounds and burns healing [81, 30, 82, 83].
In cells, pot marigold extracts increased collagen and decreased the enzyme that breaks down collagen (collagenase). Marigolds triggered the growth of cells that help repair and rebuild connective tissue (fibroblasts) and promoted new blood vessel formation (angiogenesis) [84, 31, 85, 64].
To sum up, Marigolds may improve the healing of wounds and burns by [29, 30, 31, 84, 85]:
- Promoting the formation of new blood vessels (angiogenesis).
- Increasing collagen and cells that help repair and rebuild connective tissue (fibroblasts).
- Decreasing the enzyme that breaks down collagen (collagenase).
3) Oral Health
In a clinical study on 240 people with gum disease (gingivitis), pot marigold (Calendula officinalis) mouth rinse twice/day for 6 months reduced dental plaque (mass of bacteria), gum bleeding and improved gum disease .
In a clinical study on 60 people with gum disease (gingivitis), a mouth rinse with pot marigold, rosemary, and ginger twice/day for 2 weeks decreased dental plaque (mass of bacteria), and improved symptoms compared to placebo .
In 60 people with oral inflammation and wounds in the lining of the mouth and tongue (oral leukoplakia), pot marigold gel decreased the size of the wounds within 1 month .
In 40 people with oral wounds, swelling and pain from radiotherapy, pot marigold mouth rinse reduced the symptoms and treated the wounds within 6 weeks .
In cells, pot marigold root extracts blocked the growth of the bacteria causing oral infections, teeth and gum diseases (Porphyromonas gingivalis, Fusobacterium nucleatum, Veillonella parvula) .
Overall, Marigolds may enhance oral health by [86, 87, 88, 90, 89]:
- Blocking the growth of bacteria that cause oral infections and teeth and gum diseases.
- Reducing the size and number of oral wounds.
- Improving symptoms of gum disease and mouth inflammation.
Insufficient Evidence For
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of marigolds for any of the below-listed uses. Remember to speak with a doctor before taking calendula supplements, and never use them in place of something your doctor recommends or prescribes.
In a clinical study with 150 women with vaginal yeast infections (Candidiasis), pot marigold (Calendula officinalis) vaginal cream for 30 – 35 days decreased the frequency of symptoms and improved sexual function compared to the conventional therapy (clotrimazole) .
In clinical studies with over 270 children with ear infections, 5 drops of an herbal solution containing pot marigold and other herbs (garlic, mullein, St. John’s wort, lavender, vitamin E, gordolobo) reduced ear pain better than the anesthetic ear drops [91, 92].
In cells, all marigolds ( Calendula officinalis, Calendula arvensis, Tagetes erecta, Tagetes lucida, Tagetes minuta, Tagetes patula) blocked the growth of the following bacteria [93, 9, 30, 90, 94, 95, 96, 97, 6, 14]:
- Plasmodium falciparum, which causes malaria
- Shigella flexneri, which causes diarrhea
- Various bacteria that cause urine tract, respiratory, blood and skin infections, brain, and spinal cord inflammations (such as Escherichia coli, Listeria monocytogenes, Staphylococcus, Bacillus, and Enterobacter species)
- Bacterial infections that cause complications in people with poor immunity and hospital infections (Micrococcus luteus, Pseudomonas aeruginosa)
- Bacteria that cause oral infections and teeth and gum diseases
In cells, the pot marigold, field marigold, Aztec marigold, French marigold, and wild marigold inhibited the growth of [98, 9, 99, 100, 96, 6, 14]:
- Fungi that produce aflatoxin (Aspergillus species)
- Various Candida species
- Yeast infections that cause complications in people with poor immunity (Rhodotorula albicans)
In cell studies, both pot marigold and field marigold blocked the spread of the following viruses [35, 36, 101, 102, 103]:
- HIV-1 that causes HIV infections and AIDS
- Rhinovirus (HRV), that can cause the common cold and other respiratory infections
- Epstein-Barr virus (EBV), causing mononucleosis
- Vesicular stomatitis virus (VSV), which mainly affects animals but can also cause fever, muscle pain, and weakness in humans
In a nutshell, various marigold species help fight various infections and improve symptoms by [35, 36, 37, 93, 9, 30, 98]:
- Killing bacteria.
- Inhibiting viruses.
- Blocking the growth of fungi.
5) Menstrual Cramps
In 72 young women with menstrual cramps, pot marigold (Calendula officinalis) and mint oil topical application (belly massage) reduced menstrual cramps and pain, menstrual bleeding, and the need for painkillers during menstruation .
In animal studies (guinea pigs, rabbits, rats), both pot marigold and Aztec marigold soothed muscle spasms and reduced pain in the stomach and gut [105, 106, 8].
Marigolds may relieve cramps by [105, 106, 107]:
- Blocking calcium channels, which decreases spasms and soothes the muscles.
Animal Research (Lacking Evidence)
No clinical evidence supports the use of marigolds for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
In mice, pot marigold (Calendula officinalis) lowered inflammatory cytokines (TNF-a, IL-6, beta, INF-gamma), and blocked the inflammatory Cox-2 enzyme .
In rats exposed to cigarette smoke, pot marigold increased the production of antioxidant enzymes and vitamins (superoxide dismutase, glutathione peroxidase, beta-carotene, vitamin A, vitamin C) and prevented cell injury .
In cell studies, pot marigold extract blocked the NF-κB, an inflammatory protein complex .
In cells, both pot marigold and French marigold (Tagetes patula) increased the IL-10 and lymphocytes, important for immune function [33, 34].
In cell studies, components from all marigolds decreased oxidative stress [44, 111, 112, 33, 95, 113, 45, 114, 115, 116, 117, 118, 119].
To sum it up, marigolds may decrease inflammation & oxidative stress by [108, 32, 33, 34, 44, 111, 112, 120, 109, 110, 8]:
- Their anti-inflammatory and antioxidant compounds (aradiol 3-O-laurate, palmitate, myristate, faradiol monoester).
- Their antioxidant compounds (rutin, quercetin, quercetagetin, lutein).
- Lowering inflammatory cytokines (TNF-a, IL-6, IL-1 beta, INF-gamma).
- Inhibiting Cox-2, an inflammatory enzyme.
- Blocking NF-κB, an inflammatory protein complex.
- Increasing the IL-10 production, an anti-inflammatory cytokine.
- Activating lymphocytes, white blood cells important for immune function.
- Increasing the production of antioxidant enzymes and vitamins.
7) Liver and Stomach
In rats, pot marigold (Calendula officinalis) increased the production of antioxidant enzymes (superoxide dismutase, catalase, and glutathione), reduced oxidative stress, reduced liver inflammation, and minimized liver damage [121, 122, 123].
Pot marigold also prevented stomach wounds and protected the stomach damage caused by alcohol and drugs in rats [124, 125].
In dogs and rats with ulcerative colitis, pot marigold decreased the wounds, swelling, and lowered inflammation [126, 127].
In summary, marigolds protect the liver and stomach by [121, 122, 123, 126]:
- Increasing the production of antioxidant enzymes.
- Reducing oxidative stress.
- Lowering liver and stomach inflammation.
In rats and mice, both Aztec marigold (Tagetes erecta) and Mexican marigold (Tagetes lucida) helped with depression, reduced stress and increased mobility [12, 10, 128, 129, 130, 131].
Bioactive compounds in marigolds (rutin, quercetin, dimethyl-fraxetin) may prevent depression by [132, 12, 10, 128, 129, 130, 131]:
- Increasing levels of serotonin, the happiness neurotransmitter.
- Blocking monoamine oxidase (MAO-A), a brain enzyme that breaks down neurotransmitters such as noradrenaline, adrenaline, serotonin, and dopamine.
In diabetic rats, pot marigold reduced blood sugar levels, improved diabetes-impaired learning and memory, and reduced body weight [124, 133, 134, 135].
In diabetic rats, pot marigold also decreased the high lipase, and creatine kinase levels, while increasing low amylase levels. These enzymes are linked to obesity, diabetes, and inflammation .
Altogether, marigolds may help fight diabetes by [136, 124, 133, 134, 135]:
- Lowering high blood sugar (glucose) levels.
- Decreasing high lipase, an enzyme that breaks down blood fats.
- Reducing high creatine kinase, an enzyme involved in energy production.
- Increasing low amylase levels, an enzyme that breaks down complex carbs.
10) Heart Health
High levels of blood fats and high blood pressure increase the risk of heart disease [137, 138].
In rats, pot marigold (Calendula officinalis) decreased total cholesterol, LDL cholesterol, and blood pressure [134, 135, 139].
Pot marigold stimulated the heartbeat and the blood flow in a study on hearts with reduced blood flow. It also decreased the death of heart muscle cells, preventing a heart attack .
Marigolds may protect the heart by [134, 135, 139, 140]:
- Reducing blood fats and blood pressure – the main risk factors for heart disease.
- Reducing the risk of heart attacks by increasing blood flow and stimulating the heartbeat, even when oxygen levels are low (helping muscle cells live longer).
Marigold as an Insect Repellant
In 4 men, pot marigold (Calendula officinalis) oil and myrtle oil repelled the malaria-carrying mosquito (Anopheles stephensi). However, the repellent effects lasted shorter than the chemical bug repellant (DEET) .
Pot marigold, Aztec marigold (Tagetes erecta), French marigold (Tagetes patula), and wild marigold (Tagetes minuta) extracts can repel the following insects [142, 143, 144, 145, 146, 2, 147].
- Mosquitos (Culex quinquefasciatus, Aedes aegypti, Anopheles stephensi)
- Ticks (Rhipicephalus microplus, Rhipicephalus sanguineus, Amblyomma cajennense, Argas miniatus)
- Bed bugs (Cimex lectularius)
- Winchukas (Triatoma infestans), which can cause a parasitic disease (Chagas disease)
- Fleas and flies that cause infections in cats and dogs
- Parasites and insects harmful to vegetables and plants
In cell and animal studies, various marigolds blocked the growth of cancer cells (prostate, breast, liver, melanoma, leukemia, cervix, lung, pancreas and colorectal), increased cancer cell death, and prevented metastasis [111, 95, 96, 148, 34, 149, 150, 151, 152, 153, 154, 155, 102, 6].
The following Marigolds were used:
- Pot marigold (Calendula officinalis)
- Field marigold (Calendula arvensis)
- Aztec marigold (Tagetes erecta)
- French marigold (Tagetes patula)
- Wild marigold (Tagetes minuta)
This highlights the cancer-fighting potential of completely different Marigold species that should be researched further.
All in all, marigolds may fight cancer by [111, 95, 96, 148, 34, 149, 44, 111, 112, 154, 102]:
- Killing cancer cells and blocking their growth.
- Blocking enzymes and acids cancers need to spread (hydroxyproline, uronic acid, hexosamine, blood sialic acid, and GGT).
- Supporting the immune system by increasing lymphocytes.
- Lowering oxidative stress.
Side Effects & Precautions
Both pot marigold (Calendula Officinalis) and Aztec marigold (Tagetes erecta) are generally considered safe and non-toxic [156, 157, 158, 159, 49].
People who are allergic to the daisy or sunflower (Asteraceae/Compositae) family plants, such as ragweed, chrysanthemums, chamomile, and echinacea, should avoid marigold products, as their intake may cause serious allergic reactions (anaphylactic shock) [160, 161, 162, 163, 164, 165].
Pot marigold (Calendula Officinalis) was toxic in pregnant rats when given orally. It also accelerated labor in rabbits and guinea pigs [166, 167].
Pregnant or breastfeeding women are advised to avoid all marigold products. Oral marigold should be strictly avoided, while topicals (creams/gels) are also possibly unsafe [160, 26, 1].
Pot marigold (Calendula officinalis) has a calming effect and may induce sleepiness. Taking pot marigold together with sedative drugs may cause excessive sleepiness or drowsiness. It is recommended to avoid consuming pot marigold with clonazepam, lorazepam, phenobarbital, zolpidem, and other sedative or anti-seizure drugs [26, 139].
Blood Pressure-Lowering Drugs
In rats, pot marigold lowered blood pressure. The combination with blood pressure-lowering drugs may lead to very low blood pressure [26, 139].
Blood Sugar-Lowering Drugs
In rats, pot marigold reduced blood sugar levels. The combination with blood sugar-lowering drugs may further lower blood sugar [26, 124, 133].
In rats, pot marigold (Calendula officinalis) decreased total cholesterol and LDL cholesterol. The combination with cholesterol-lowering drugs may increase this effect [26, 134, 135].
To avoid adverse effects or unexpected interactions, talk to your doctor before using marigold.
Limitations and Caveats
There are sufficient clinical trials examining the effect of marigolds on skin health and wound healing. Other health benefits are supported mainly by animal and cell studies, or clinical studies with a small number of participants.
Moreover, most research is focused on Calendula plants and not on the Tagetes family plants.
More research would provide additional information about the risks and health benefits of marigolds.
Various species of marigolds have been used in different parts of the world – from the Aztec marigold, used to adorn ceremonies and in folk medicine to soothe depression, to Mediterranean marigold or calendula, a traditional remedy for skin irritation and inflammation in Europe. Modern research has begun to uncover the potential of marigolds for human health.
Watch out for allergic reactions, especially if you react to other plants of the daisy/sunflower family (Asteraceae).