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.
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.
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.
- 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
- 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
- Minerals (iron, copper, magnesium, calcium, zinc)
- Phenolic acids
- Fatty acids
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.
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].
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].
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 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].
- 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).
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) .
- 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.
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
- Fungi that produce aflatoxin (Aspergillus species)
- Various Candida species
- Yeast infections that cause complications in people with poor immunity (Rhodotorula albicans)
- 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
- Killing bacteria.
- Inhibiting viruses.
- Blocking the growth of fungi.
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 .
- Blocking calcium channels, which decreases spasms and soothes the muscles.
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 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 .
- 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.
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].
- Increasing the production of antioxidant enzymes.
- Reducing oxidative stress.
- Lowering liver and stomach inflammation.
- 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.
- 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.
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 .
- 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).
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) .
- 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.
- 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.
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) 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].
To avoid adverse effects or unexpected interactions, talk to your doctor before using marigold.
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).