Boswellia

Boswellia (Boswellia serrata): A Comprehensive Reference

1. Identity, Taxonomy, and Natural Source

Botanical name: Boswellia serrata Roxb. ex Colebr. The genus Boswellia belongs to the family Burseraceae and is found in South Asia, Northern Africa, and the Middle East. The tree is a moderate-to-large-sized, deciduous member of the Burseraceae family; the genus Boswellia contains 28 different species, including Boswellia frereana (elemi frankincense), Boswellia papyrifera (elephant tree), and Boswellia sacra (frankincense, olibanum). Boswellia serrata is a deciduous tree found in dry parts of India and China.

Common names: Other common names include Indian frankincense and shallaki. In the vernacular, the gum resin is known as "Sallai guggal." Among the commercially important species, Boswellia serrata, B. frereana, B. sacra, and B. papyrifera are the principal sources of medicinal frankincense.

The resin: The resin is obtained after the coagulation, drying, and purification of the sticky and milky liquid that is secreted when the bark of the Boswellia tree is incised at the trunk and branches. Oleo-gum-resin is collected from wild trees by making incisions in the bark of the trunks. The resulting dried resin is the raw material for all commercial preparations.

Common preparations and dosage forms: Boswellia can be taken orally in a capsule, pill, or tablet, or used as an oil applied to the body. Boswellia extract contains essential oils, terpenoids, sugars and volatile oils, and prominently several pentacyclic triterpene acids such as beta boswellic acid. Standardized extracts represent the most clinically studied form; several forms of Boswellia serrata have been studied and used clinically, including traditional 60% to 70% extracts of Boswellia serrata gum resin and the commercial preparations 5-Loxin and Aflapin.

2. Traditional and Historical Use

In ancient times, frankincense was burned during religious ceremonies and rituals to perfume worship places and to prevent the spread of contagion in crowded areas. Both antimicrobial and antifungal properties have been recognized in frankincense smoke.

Boswellia, also called Indian Frankincense, is an extract of the gummy oleoresin derived from beneath the bark of the Boswellia serrata tree, which is native to India, the Middle East, and Northern Africa. The resin is rich in triterpenic acids and has been used for centuries in traditional Ayurvedic medicine to treat inflammatory conditions.

The resin of the Boswellia tree, known as frankincense or olibanum, is used in Ayurveda to treat arthritis, ulcerative colitis, coughs, sores, asthma, and for wound healing. The gum resin has been used in the Ayurvedic system of medicine for the management of rheumatism, respiratory diseases, and liver disorders.

The plant has deep religious and cross-cultural significance. In Christian tradition, frankincense was one of the three gifts offered to the infant Jesus. The resin is also mentioned frequently in the Jewish Pentateuch. Roman author Pliny the Elder mentioned frankincense as an antidote to hemlock poisoning. In Ayurveda, Unani, and Middle Eastern medicine, frankincense has been used for inflammation, arthritis, and respiratory ailments.

3. Key Constituents and Active Compounds

3.1 Boswellic Acids

Various B. serrata extracts and its gum resins have been shown to possess pharmacologically important phytocompounds such as boswellic acid (BA), a pentacyclic triterpenic acid, and its derivatives acetyl-β-boswellic acid, 11-keto-β-boswellic acid, and 3-O-acetyl-11-keto-β-boswellic acid (AKBA).

Six major boswellic acids, namely keto-β-boswellic acid (KBA), 3-O-acetyl-11-keto-β-boswellic acid (AKBA), α-boswellic acid (α-BA), β-boswellic acid (β-BA), 3-O-acetyl-α-boswellic acid (α-ABA), and 3-O-acetyl-β-boswellic acid (β-ABA), are responsible for the anti-inflammatory activities of the Boswellia gum resin. These boswellic acids exist in either α-configuration (geminal methyl groups at C-20) or β-configuration (vicinal methyl groups at C-19/C-20). Other structural characteristic features include the presence of a carbonyl moiety at C-11 in 11-keto-BAs and an acetyl moiety on the C-3 OH group in 3-O-acetyl-BAs. Besides, a carboxyl group is present in all six boswellic acids at C-24.

These compounds make up approximately 14% of the lipophilic fractions of B. serrata extract and are the major active components. Various pharmacological studies suggest that the β-configured derivatives of boswellic acids from B. serrata extract exhibit significantly better efficacy than their corresponding α-isomers.

3.2 Other Phytochemical Components

The majority of compounds in B. serrata are triterpenoids belonging to boswellic acids and tirucallic acid type metabolites. The chemical composition of the Boswellia oleogum resin is based on the ether solubility of its components. The ether-insoluble fraction mainly consists of polysaccharides, while the ether-soluble fraction contains a large variety of terpenes and terpenoids.

4. Mechanisms of Action

4.1 5-Lipoxygenase (5-LOX) Inhibition

In vitro studies revealed that boswellic acids, a group of pentacyclic triterpenoid compounds, and their acetylated derivatives inhibit the biosynthesis of leukotrienes, the proinflammatory 5-lipoxygenase products which cause increased permeability, in a dose-dependent manner. Among the boswellic acids, 3-acetyl-11-keto-beta-boswellic acid (AKBA) potently inhibits 5-lipoxygenase product formation with an IC50 of 1.5 μM.

In the study by Siemoneit et al., the inhibitory effects of different boswellic acids on 5-LOX were evaluated across various in vitro test systems, including purified 5-LOX enzyme, supernatants of E. coli lysates, and neutrophils. Both AKBA and KBA demonstrated strong inhibition of 5-LOX across all systems. Notably, in the presence of albumin (10 mg/mL), the inhibitory effect of 11-keto boswellic acid (up to 30 μM) on neutrophil 5-LOX was abolished.

5-LOX is the key enzyme in leukotriene synthesis, producing leukotrienes (particularly LTB4) that drive neutrophil recruitment, vascular permeability, and synovial inflammation. The 5-LOX pathway is also involved in leukotriene-mediated cartilage degradation — LTB4 activates metalloproteinases that break down collagen and proteoglycans directly.

4.2 NF-κB Inhibition

Cuaz-Pérolin et al. observed that 3-acetyl-11-keto-beta-boswellic acid (AKBA) was a natural inhibitor of the transcription factor NF-κB, whose presence is a prerequisite for the formation and action of cytokines and chemokines involved in inflammatory reactions.

4.3 Additional Molecular Targets

Boswellic acids have also been investigated against cathepsin G, microsomal prostaglandin E synthase-1, NF-κB signalling, and matrix metalloproteinases. Most such findings come from purified-enzyme, cell, or animal experiments and remain proposed mechanisms rather than confirmed clinical pathways.

Studies in animal models showed that the ingestion of a defatted alcoholic extract of Boswellia decreased polymorphonuclear leukocyte infiltration and migration as well as primary antibody synthesis, and led to almost total inhibition of the classical complement pathway.

4.4 Contrast with NSAIDs

NSAIDs generally act through cyclooxygenase inhibition, whereas Boswellia preparations have a different and more complex experimental target profile. AKBA selectively inhibits 5-LOX without meaningfully affecting COX enzymes. This selectivity matters clinically: COX-1 inhibition causes GI mucosal damage, a major NSAID side effect, which Boswellia avoids.

4.5 Bioavailability Considerations

There is significant evidence suggesting the anti-inflammatory properties of gum resin extracts of Boswellia serrata containing AKBA, but the poor bioavailability of AKBA following oral administration might limit the anti-inflammatory efficacy of standardized Boswellia extracts. AKBA has shown poor absorption after oral administration due to its high log P and poor aqueous solubility. Another research group reported that keto-boswellic acids (KBAs) inhibit the transport activity of P-glycoprotein, which may impact absorption through the intestinal wall.

Pharmacokinetic reviews have questioned whether circulating concentrations of KBA and AKBA after conventional oral extracts are high enough for 5-lipoxygenase inhibition to explain all clinical effects. The bioavailability of AKBA is limited by its hydrophobicity and poor water solubility. Combining AKBA with non-volatile oils, as in proprietary formulations such as ApresFlex® and Aflapin®, has been shown to enhance absorption.

The availability of AKBA in systemic circulation of experimental animals is increased by 51.78% in Aflapin-supplemented animals, in comparison with 30% AKBA standardized extract (5-Loxin®). In animal studies, following a single oral dose of Boswellia serrata extract, both KBA and AKBA have been detected in plasma as well as in brain tissue. In a rat model reported by Reising et al. (2005), KBA reached concentrations of approximately 99 ng/g in brain tissue, while AKBA was found at about 95 ng/g. In these animals, plasma levels were considerably higher, with KBA generally ranging between 150 and 200 ng/mL.

5. Scientific Evidence by Area of Use

5.1 Osteoarthritis

Osteoarthritis, particularly of the knee, represents the most extensively studied indication for Boswellia. The strongest clinical evidence for Boswellia serrata is in osteoarthritis. A systematic review and meta-analysis pooling data from multiple randomized controlled trials found that Boswellia significantly improved pain, stiffness, and physical function compared to placebo.

Seven trials involving 545 patients were included in a 2020 meta-analysis. Compared with the control group, Boswellia and its extract may relieve pain (VAS: WMD −8.33; 95% CI −11.19, −5.46; P<0.00001; WOMAC pain: WMD −14.22; 95% CI −22.34, −6.09; P=0.0006) and stiffness (WOMAC stiffness: WMD −10.04; 95% CI −15.86, −4.22).

A systematic review of 20 randomized controlled trials found that Boswellia serrata extracts, particularly in modified formulations, significantly improved joint function in patients with mild to moderate knee osteoarthritis. A systematic review and network meta-analysis of 39 randomized controlled trials found that Boswellia significantly improved pain, stiffness, and function in patients with knee osteoarthritis.

Aflapin, containing Boswellia serrata extract enriched with at least 20% AKBA and the non-volatile oil portion of Boswellia serrata gum resin, was evaluated against 5-Loxin or placebo in a 90-day trial, both dosed at 100 mg/day. Both products resulted in significant improvement in VAS, WOMAC pain, function and stiffness, and LPFI scores, with Aflapin showing improved efficacy in as early as 7 days. Aflapin was again evaluated in a 30-day trial, which led to significant improvements in the pain and physical function WOMAC subscores, Lequesne and VAS scores in as early as 5 days.

In multiple randomized, double-blind, placebo-controlled trials, formulations enriched in boswellic acids — such as Boswel®, Aflapin®, and 5-Loxin® — were found to significantly improve pain scores, joint stiffness, and functional impairment. Some formulations also demonstrated the ability to reduce inflammatory markers such as TNF-α, IL-6, CRP, and matrix metalloproteinases (MMPs).

Improvement in symptoms was noticed as early as 5 days after treatment commenced, and in one trial these benefits persisted for 1 month following conclusion of treatment. Daily dosages used in these studies were 100 mg of Aflapin, 250 mg of 5-Loxin, and 333 mg of 65% standardized Boswellia serrata extract. Boswellia serrata was well tolerated in all trials, and aside from minor gastrointestinal distress in some participants, very few adverse effects were noted.

Limitations: Several studies have examined the potential health benefits and safety of using Boswellia, but most are small and of low quality. There is not enough high-quality evidence to determine whether Boswellia is useful for any health condition. Several studies have shown taking Boswellia orally may help reduce inflammation and pain associated with osteoarthritis, but larger, higher quality studies are needed.

5.2 Asthma and Respiratory Conditions

Boswellic acid has shown significant pharmacological activity in the treatment of inflammatory diseases such as rheumatoid arthritis, chronic bronchitis, asthma, and chronic inflammatory bowel diseases. For asthma, a double-blind, placebo-controlled study over six weeks found that 70% of patients taking Boswellia experienced measurable improvement. Their breathing capacity increased, the number of asthma attacks decreased, and blood markers of allergic inflammation dropped. This aligns with the 5-LOX mechanism, since leukotrienes are major drivers of airway constriction and allergic inflammation in the lungs.

This study — the 1998 Gupta et al. trial published in the European Journal of Medical Research — examined effects of Boswellia serrata gum resin in patients with bronchial asthma in a double-blind, placebo-controlled, 6-week clinical study. Limitations: This study represents a single, relatively small trial, and evidence remains preliminary; independent replication in larger studies is lacking.

5.3 Inflammatory Bowel Disease

Ulcerative Colitis (UC): A small trial of active UC patients found that Boswellia 350 mg three times a day was as effective as sulfasalazine 1,000 mg three times a day in decreasing symptoms and laboratory indicators. A second similar study of 30 active UC patients again found Boswellia to be as effective as sulfasalazine, with remission rates of 82% and 75%, respectively. Boswellia serrata at a dose of 350 mg thrice daily for 6 weeks achieved remission in 82% of treated UC patients compared to 75% of patients who were treated with sulfasalazine.

Crohn's Disease: Boswellia has also been tested in Crohn's patients for initiating and maintaining remission. Out of 83 patients with Crohn's disease — 44 treated with H15 (a Boswellia serrata preparation) and 39 treated with mesalazine — the Crohn Disease Activity Index was reduced by 90 points after treatment with H15 and by 53 points after therapy with mesalazine in the mean. However, evidence is unclear or negative surrounding Boswellia's effectiveness against collagenous colitis, with no significant benefit found in maintaining remission in patients with Crohn's disease in at least one later trial.

Overall IBD limitations: While some RCTs have shown that B. serrata extract may provide clinical benefits for conditions such as rheumatoid arthritis, ulcerative colitis, and asthma, these studies are often limited by small sample sizes, variable control settings, short follow-up periods, and a lack of biomarker validation — rendering the evidence insufficient for firm conclusions.

5.4 Rheumatoid Arthritis

In a study of 78 rheumatoid arthritis outpatients, NSAID use declined 5.8% in the Boswellia group vs. 3.1% in the placebo group, but no other benefit was noted in this trial at 9 tablets (3,600 mg) Boswellia or placebo daily. The topical use of Boswellia (frankincense) for rheumatoid arthritis and other health conditions has been studied, but there is not enough evidence to show that it is an effective treatment. The evidence base for rheumatoid arthritis is considerably weaker than for osteoarthritis.

5.5 Radiation-Induced Cerebral Edema

A randomized, placebo-controlled, double-blind study investigated the efficacy of Boswellia serrata on cerebral edema in patients irradiated for brain tumors. Patients taking BS extract had significantly less cerebral edema than patients taking placebo, while the median dexamethasone dosage was the same in both groups.

Specifically, forty-four patients with primary or secondary malignant cerebral tumors were randomly assigned to radiotherapy plus either BS 4,200 mg/day or placebo. The volume of cerebral edema in the T2-weighted MRI sequence was analyzed as a primary endpoint. A reduction of cerebral edema greater than 75% was observed in 60% of patients receiving Boswellia, compared with only 26% in the placebo group. There were no severe adverse events in either group. Boswellia could potentially be steroid-sparing for patients receiving brain irradiation. These findings will need to be further validated in larger studies.

A systematic review of 6 human studies found nearly half of the patients benefiting from the use of boswellic acid from Boswellia serrata in the treatment of radiation-induced cerebral edema and radiation necrosis, though the evidence remained limited.

5.6 Cancer — Preclinical Evidence Only

Many recent research studies showed that boswellic acid has anticancer effects. Boswellic acids have been shown to modulate and potentiate apoptosis through caspase-8 activation and death receptor 5–mediated signalling in several types of tumor cells, including colon cancer, prostate cancer, fibrosarcoma, hepatoma, and malignant glioma cells. In human myeloid KBM-5 cells, AKBA appears to potentiate cytotoxicity induced by classical chemotherapeutic agents (doxorubicin, 5-fluorouracil) secondary to NF-κB inhibition.

These findings are preclinical only. No human clinical trials have established Boswellia as a cancer treatment, and the anticancer data should be interpreted solely in that context.

5.7 Immune Modulation

Extracts from the gum resin of Boswellia serrata and some of its constituents including boswellic acids affect the immune system in different ways. Among the various boswellic acids, 11-keto-beta-boswellic acid (KBA) and acetyl-11-keto-beta-boswellic acid have been observed to be active. However, other boswellic acids may also exhibit actions in the immune system. In the cellular defense, boswellic acids appear to increase lymphocyte proliferation at lower concentrations, whereas higher concentrations are inhibitory. Moreover, boswellic acids increase phagocytosis of macrophages. They also affect the cellular defense system by interaction with the production and release of cytokines.

6. Body Systems Associated with Boswellia

• Musculoskeletal system: The best-evidenced application. Studied for osteoarthritis and rheumatoid arthritis, with multiple RCTs and meta-analyses for osteoarthritis of the knee showing positive effects on pain, stiffness, and function.
• Gastrointestinal system: The powdered gum resin and extracts obtained from Boswellia spp. have been used as dietary supplements for the treatment of various inflammatory and gastrointestinal diseases. Clinical trials have examined UC and Crohn's disease, with moderate but mixed evidence.
• Respiratory system: Boswellic acids are traditionally used as antioxidants and anti-inflammatory agents for treating conditions such as rheumatoid arthritis, chronic bronchitis, asthma, and chronic inflammatory bowel diseases. The asthma double-blind trial demonstrated improvement, though larger replication is lacking.
• Neurological / Oncological (supportive): Preliminary RCT evidence for radiation-induced cerebral edema in brain tumor patients at 4,200 mg/day.
• Immune system: Modulation of lymphocyte proliferation, macrophage phagocytosis, and cytokine profiles observed in immunological studies.

7. Dosage Forms and Dosages Reported in Clinical Studies

Boswellia serrata extract in doses up to 1,000 mg daily has been safely used in several clinical trials lasting up to 6 months. It has also been used with apparent safety at a dose of 2,400 mg for up to 1 month.

Specific dosages reported in studies include:

• Daily dosages of 100 mg of Aflapin, 250 mg of 5-Loxin, and 333 mg of 65% standardized Boswellia serrata extract were used in osteoarthritis clinical trials.
• Boswellia 350 mg three times a day (1,050 mg/day total) was tested in ulcerative colitis trials.
• 4,200 mg/day was used in the brain tumor cerebral edema pilot trial.
• 3,600 mg/day (9 tablets) was used in the rheumatoid arthritis trial by Sander et al.

5-Loxin® is a Boswellia serrata extract standardized to 30% AKBA. Aflapin contains Boswellia serrata extract enriched with at least 20% AKBA and the non-volatile oil portion of Boswellia serrata gum resin.

Taking Boswellia with a fat-containing meal significantly increases AKBA plasma concentrations. The amounts of each chemical in a specific Boswellia serrata product may vary, and different amounts of boswellic acids may change the effects of Boswellia serrata on the body.

8. Safety Considerations

8.1 General Tolerability

Boswellia serrata is considered a safe dietary supplement with no severe long-term side effects. Mild side effects such as diarrhea, abdominal pain, and vomiting may occasionally occur. However, there is no evidence of severe side effects associated with the use of Boswellia serrata.

In randomized controlled trials of osteoarthritis patients, standardized Boswellia extracts such as 5-Loxin® and Aflapin® were generally safe, with most adverse events being mild gastrointestinal symptoms (e.g., nausea, diarrhea, abdominal pain) and occurring at rates comparable to placebo.

Side effects from Boswellia serrata are generally mild and often occur with a placebo as well during clinical trials.

8.2 Hepatotoxicity

Extracts of Boswellia serrata have not been linked to serum aminotransferase elevations during treatment or to instances of clinically apparent acute liver injury.

8.3 Pregnancy and Lactation

There is limited data about the safety of Boswellia serrata in pregnancy and lactation, and avoidance is warranted. Due to a lack of studies, it is not recommended for use during pregnancy and breastfeeding.

8.4 Drug Interactions

Boswellia serrata has minimal reported drug interactions. Boswellia may have moderate interactions with drugs metabolized by the liver. The fact that Boswellia preparations do not share the COX-inhibitory mechanism of NSAIDs does not prove freedom from gastrointestinal, cardiovascular, renal, bleeding, or drug-interaction risks. Safety must be established from clinical observation and pharmacovigilance, not inferred from the absence of a single COX mechanism.

8.5 Contraindications

Contraindications include known allergies to boswellic acids. Reported side effects in order of frequency include: abdominal pain, diarrhea, loss of appetite, heartburn, nausea/vomiting, and allergic reaction to boswellic acid.

8.6 Preclinical Toxicological Data

A 90-day gavage study in rats found that Boswellia serrata is relatively safe up to the dose of 500 mg/kg body weight per day, as no adverse impact on health factors was observed. The No Observed Adverse Effect Level (NOAEL) was established at 500 mg/kg body weight per day.

8.7 WADA Status

According to the 2026 WADA List of Prohibited Substances, Boswellia serrata is not prohibited.

9. Overall Evidence Assessment

The strongest and most consistent clinical evidence for Boswellia serrata is in osteoarthritis of the knee, where multiple RCTs and meta-analyses show statistically and clinically significant reductions in pain, stiffness, and functional impairment. While some RCTs have shown that B. serrata extract may provide clinical benefits for conditions such as rheumatoid arthritis, ulcerative colitis, and asthma, these studies are often limited by small sample sizes, variable control settings, short follow-up periods, and a lack of biomarker validation. Most existing clinical studies have employed Boswellia serrata extract as the intervention, which contains a complex mixture of metabolites with undefined BA content. This complexity makes it difficult to attribute therapeutic effects specifically to boswellic acids, thereby limiting the translation of mechanistic findings to human applications.

Mechanistic findings — particularly 5-LOX and NF-κB inhibition — are well-characterized in vitro and in animal models, but many precise molecular mechanisms remain proposed rather than confirmed in human clinical settings. Evidence for cancer applications is currently preclinical only. The cerebral edema indication is supported by a single small RCT and a limited systematic review, warranting further study.

References

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