Calendula (Calendula officinalis): Benefits, Uses, Safety and Dosage

Calendula is a short-lived perennial herb belonging to the family Asteraceae. It is also called pot marigold or garden/English/Mary marigold. It is native to southern Europe, Italy, Greece, and North Africa. It is currently cultivated in North America and Canada, the United Kingdom, the Balkans, India, Australia, and New Zealand.

Calendula is used in the following ways:

• In wounds like diaper rash, venous leg ulcers, and episiotomy recovery.
• Reducing inflammation in patients undergoing radiation therapy
• In vaginal candidiasis (yeast infection)
• In oral health aganst plaque and gingivitis
• Ear drops for pain and infections

Medical Uses and ethnoparmacological profile of Calendula

Traditional Uses

It was used as a vulnerary (used on wounds to avoid putrefaction and to solder wound edges). In the digestive tract, it was used as a cholagogue to stimulate bile flow and cleanse the liver and for soothing gastritis by coating the stomach walls. The compress and/or calendula tea were used on swollen lymph nodes around the neck, groin, or armpit area. It was also used as a post-illness tonic.

Clinical Uses and Research

Mask-induced acne: In adults with acne, a hydroalcoholic flower extract serum (licorice/snail filtrate and calendula) applied twice daily for 12 weeks reduced inflammatory acne lesions compared to the placebo group. It worked well as an adjuvant to stimulate new blood vessel growth and fibroblast migration that aided skin healing of tiny tears caused by mask friction.

It also exhibited mild antibacterial and anti-inflammatory properties. Identified compounds were faradiol ester, calendulosides, quercetin, and luteolin.

Venous Leg Ulcer: Flower hydroglycolic extract given twice daily for 30 weeks exhibited a 72% complete healing in the treatment group and a 4 times faster healing velocity. Triterpenes, saponins, and flavonoids stimulated angiogenesis and collagen synthesis, thus reducing proinflammatory cytokines. (Buzi 2016)

Vaginal candidiasis: In women with yeast infections, a flower 5% calendula vaginal cream at a dose of 5 grams intravaginally for 7 nights showed efficacy comparable to clotrimazole in clearing the infection as well as reducing itching and discharge. Essential oils and calendulosides disrupted fungal cell membranes and also inhibited NF-kB to reduce inflammation.

Pain in post-breast cancer operation: During radiation therapy, in patients with radiation dermatitis, Flower 10% ointment applied twice daily throughout radiation lowered pain scores with action comparable to trolamine and also reduced grade 2+ dermatitis. This was through the action of fradiols and carotenoids that inhibited the synthesis of prostaglandins and cyclooxygenase synthesis to reduce pain and inflammation while also scavenging for free radicals, inducing an antioxidant effect.

Wound healing (2^nd degree burns): The flower’s oral ethanol extract at a dose of 2 grams daily for 15 days improved wound contraction and healing from day 7 as compared to the control group. The compounds quercetin and isohamnetin improved blood flow to injured tissue and accelerated epithelization and fibroblast migration.

In Vivo Uses and Research

Hepatoprotective: In Wistar rats with liver damage, flower ethanolic extract at a dose of 250-500 mg/kg orally for 15 days showed reduction in AST/ALT/ALP levels and reversal of liver tissue necrosis. Flavonoids and phenolics acted by scavenging free radicals and enhancing the levels of antioxidant enzymes like CAT.

Anxiety/sedation: In a male mice model, flower ethanolic extract given at a dose of 100-200 mg/kg orally increased sleep duration and reduced locomotor activity, exhibiting mild sedative effects. This was via potential modulation of GABA activity suspected to be induced by volatile flavonoids. (Shivasharan 2013)

Hyperlipidemia: In Wistar rats, standardized flower extract at an oral dose of 250 mg/kg for 4 weeks reduced levels of triglycerides and low-density lipoproteins while increasing the levels of high-density lipoproteins. Lutein inhibited pancreatic lipase, thus modulating lipid metabolism and reducing the uptake of fats from the intestines.

In Vitro Uses and Research

Antibacterial: In cultures of S. aureus and E. coli, flower essential oil and methanolic extract worked against both gram-negative and gram-positive (moderately) bacteria. Cardinol, terpenoids, and saponins inhibited the respiratory enzymes in the microbes, thus causing their death.

UV protection: In human keratinocytes, the flower carotenoid fraction prevented UV-induced DNA damage and lipid peroxidation on the skin. Lutein, beta carotene, and zeaxanthin scavenged reactive oxygen species generated by UVB radiation. (Abdullah 2016)

Anticancer: In melanoma cells, flower methanolic extract showed inhibition of cancer cell proliferation with selectivity. Calenduloids induced cell cycle arrest at the G2/M phase.

Safety and Dosing profile of Calendula

Forms and Dosing

Infused oils– applied 2-3 times daily

Salves and balms– applied 2-3 times daily

Creams and lotions– applied 2-3 times daily

Toners and serums– applied twice daily

Poultices

Tea– 1-3 cups daily

Powders– 1-2 grams

Tinctures (1:5)– 1-2 mls thrice daily

Fresh petals

• Radiation dermatitis- 10% ointment applied thrice a day
• Venous leg ulcers- 7-10% ointment three times a day
• Oral mucositis- 2% as a mouthwash up to 4 times a day
• Inflammatory skin conditions- 2-5% cream thrice a day

Note: If being consumed internally, do not exceed 3 grams a day, and it should not be taken chronically without breaks.

Interactions

If ingested (because topical application is encouraged over ingestion), possible drug interactions include:

• CNS depressants- risk of drowsiness
• Anti-diabetics- risk of hypoglycemia
• Anti-hypertensives- risk of hypotension

Side effects

• Allergic reactions like contact dermatitis
• Nausea and diarrhea
• Early menstruation
• Excessive drowsiness in large amounts

Contraindications

• Known allergy
• Pregnancy and breastfeeding
• Puncture/deep wounds
• 2 weeks to surgery