Nutritional Supplements

Ascorbic acid, or vitamin C, is used to treat infectious rhinitis (common cold) with 1 to 3 g by mouth daily, and allergic rhinitis as an intranasal topical medication. It seems to inhibit histamine secretion by lymphocytes, showing an inverse correlation of plasma ascorbic acid levels with histamine levels. Although ascorbic acid does not prevent acute viral rhinitis from the common cold, it may shorten the disease course by 1 to 1.5 days. Comparisons of intranasal ascorbic acid with placebo in allergic rhinitis have shown decreased nasal secretions, congestion, and edema in subjects treated with ascorbic acid solution. Potential severe side effects include kidney stones, severe diarrhea, delayed healing, increased iron absorption in blood-iron disorders (thalassemia, hemochromatosis), and worsening of sickle cell disease. Drug interactions include decreased effectiveness of HIV/AIDS medications amprenavir (Agenerase), nelfinavir (Viracept), ritonavir (Norvir), and saquinavir (Fortovase, Invirase). Large amounts of ascorbic acid may decrease the effectiveness of warfarin (Coumadin), requiring dose alterations, and can delay the metabolism of aspirin, potentiating its effects.

Capsaicin (8-methyl- n -vanillyl-6-nonenamide) is the natural product of chili peppers that produces their burning heat. It is assumed to block neuropeptides like substance P, affecting pain transmission. Substance P is also released from nasal mucosal cells, interacting with nasal innervation and increasing interleukin (IL)-6 production, potentially at greater levels in allergic rhinitis. Capsaicin is used in topical applications for pain relief from muscular soreness and peripheral neuropathy, but investigations of capsaicin for treatment of allergic rhinitis to dust mites did not find any therapeutic effect. No drug interactions are known, and systemic side effects are rare, but localized irritation can occur at the application site.

Fish oil contains eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) acids, ω-3 fatty acids known to have antiinflammatory properties benefiting chronic inflammatory conditions. Similarly, cod liver oil, produced from the livers of cod, halibut, and other white fish, contains long-chain fatty acids as well as vitamin D, and shares the antiinflammatory properties of fish oil. Reduced intake of fish oil fatty acids may be associated with an increase in allergic rhinitis prevalence. Limited benefit has been shown in other allergic diagnoses like asthma and atopic dermatitis. However, information on the effects of fish oil on allergic rhinitis is minimal or conflicting between studies, with one double-blinded, placebo-controlled study resulting in no significant differences, whereas cross-sectional studies may show reduced prevalence of allergic rhinitis with increased intake of fish oil. The ω-3 fatty acids exert a dose-related increase on bleeding time, and should be used with caution in patients with bleeding disorders, on blood-thinning medications, or before elective surgery. Fish oil can decrease blood pressure and increase the effect of hypertensive medications, leading to hypotension.

Spirulina is dried filamentous cyanobacteria from blue-green algae Arthospira platensis and is high in protein, vitamin B12 and provitamin A (β-carotenes), and minerals like iron. It is known to have antiinflammatory effects through inhibition of histamine release from mast cells, and high doses of spirulina significantly reduce IL-4 in the immunoglobulin (Ig)-E–mediated allergy pathway, and enhance IgA production. One randomized-control trial confirmed the decrease in IL-4 and improvement in nasal symptom scores in patients with allergic rhinitis after 6 months of spirulina dosing. Hepatotoxicity and reactions from heavy-metal contamination have been reported but no drug interactions are known.

Herbal Medications

Bromelain is a stem and fruit extract from pineapple ( Ananas comosus ) containing a proteolytic enzyme complex that has been used as a mucolytic and antiinflammatory. Use of bromelain has been shown to thin nasal mucus secretions, and is an effective mucolytic for the respiratory tract. Proteolysis at sites of inflammation also seems to inhibit the production proinflammatory prostaglandins like prostaglandin E1. A recent study from 2005 found statistically faster symptomatic recovery from sinusitis with bromelain compared with placebo. Possible side effects are gastrointestinal upset and rare allergic reactions, with possible overlap with allergies to pineapple, wheat, celery, papain, carrot, fennel, cypress pollen, or grass pollen. Oral dosing of bromelain is typically 500 to 1000 mg/d or up to 2000 mg.

Garlic ( Allium sativum ) is often used for treatment of cough, viral upper respiratory infections, and rhinitis by oral dosing or direct nasal topical application. Potential adverse effects include rare allergic reactions, hypoglycemia, and prolonged bleeding time. Garlic also influences the cytochrome P450 system, potentiating the anticoagulant effect of warfarin. Alterations of pharmacokinetics may also interfere with paracetamol and chlorpropamide, resulting in hypoglycemia, or ampicillin with increased minimal inhibitory concentration reported. Garlic is associated with decreased platelet aggregation within 5 days of oral dosing in a dose-dependent manner, with the possible mechanism being from inhibition of epinephrine-induced platelet aggregation. Irreversible platelet effects from ajolene, another active compound in garlic, can increase the effects of other platelet inhibitors. Discontinuing garlic intake 1 week before elective surgery is suggested. Although few published reports of bleeding complications have been connected to garlic, there are definitive reports of increased international normalized ratios (INRs) and prothrombin times with coinciding garlic and coumadin dosing.

Quercetin (3,3′,4′,5-7-pentahydroxyflavone) is a plant-derived flavonoid found in fruits, vegetables, leaves, and grains and exhibits in vitro antiinflammatory activity from antioxidant properties and inhibition of inflammatory enzymes (cyclooxygenase and lipooxygenase, regulators of leukotrienes and prostaglandins). In addition,, quercetin is able to stabilize mast cells to inhibit the release of histamine, even after IgE activation, and provides a clinical function similar to cromolyn sodium, although no definitive evidence of effect has been shown in clinical trials. Oral dosing with 400 to 500 mg 3 times daily is common. No side effects have been reported, but quercetin may lessen the effects of quinolone antibiotics, and these should not be taken simultaneously.

Butterbur ( Petsites hybridus ) is an extract from the leaves and roots of the butterbur shrub, and contains the active ingredient sesquiterpenes (petasins) that may inhibit leukotriene, mast cell degranulation, and histamine synthesis. Butterbur has been shown to significantly reduce the symptoms of allergic rhinitis in randomized, double-blinded, placebo-controlled studies, and is similar in efficacy to cetirizine and fexofenadine, although other studies showed minimal effect. Critical to the safety profile of butterbur is the processing of raw butterbur extract to remove pyrrolizidine alkaloids that are hepatotoxic and carcinogenic. Petasin is a processed butterbur extract with the alkaloids removed, and is approved for allergic rhinitis treatment in Switzerland. Adverse effects include only rare gastrointestinal complaints, although the mechanism of action and long-term effects are poorly understood.

Sinupret is a herbal preparation used widely in Europe, including extracts of elder flowers ( Sambucus nigra ), cowslip flowers ( Primula veris ), common sorrel ( Rumex acetosa ), European vervain ( Verbena officinalis ), and gentain ( Gentaina lutea ) root. Of 4 larger studies, 3 showed positive efficacy with antiviral, antiinflammatory, and mucus-thinning properties. Reported adverse events included kidney stones, allergic reactions, gastrointestinal symptoms, numbness, and mild dermatitis. Sinupret interacts with therapeutic monoclonal antibodies (eg, adalimumab [Humira], bevacizumab [Avastin], infliximab [Remicade], and omalizumab [Xolair]), hypertensive medications, and immunosuppressants (tacrolimus, methotrexate, corticosteroids, mycophenolate, etanercept, and cyclosporine), and is not recommended in patients with hypertension, immunosuppression, or a history of kidney stones.

Echinacea ( Echinacea purpurea leaf and Echinacea pallida contain active components) is a herb shown to activate T and B lymphocytes in vitro, leading to a potential application for viral rhinitis symptoms, and although several meta-analyses found positive effects, some studies have shown no effect. As is true with many herbal medications, commercially available formulations of echinacea also vary widely in amount and type of active compounds, further complicating effective studies. Gastrointestinal upset, tongue numbness, headache, muscular aches, and dizziness can occur, and echinacea has been associated with hepatotoxicity after prolonged use beyond 8 weeks. Echinacea can delay the metabolism of caffeine, causing tachycardia and nervousness, and it increases the activity of the immune system, which could directly counteract any immune-suppressive medications.

Esberitox contains 3 herbs ( Thuja occidentalis , Echinacea angustifolia , and Baptisia tinctoria ) and acts as an immune stimulant. Studies comparing Esberitox with placebo and other CAM and traditional therapies showed good effect as an adjunct to doxycycline for treatment of acute sinusitis, with significant effect compared with placebo. No drug interactions are known, but uncommon side effects like rashes, itching, facial swelling, vertigo, and hypotension have been described.

Stinging nettle ( Urtica doica ) is used for the treatment of allergic rhinitis, but double-blind randomized studies have shown no, or only subjective, benefit.

Myrtol is a herbal extract with components from Pinus spp (pine), Citrus aurantifolia (lime), and Eucalyptus globulus . Some effect compared with placebo has been shown, with symptom reduction similar to other herbal therapies but insufficient data to show significance. Possible adverse effects included gastrointestinal disturbance, facial swelling and allergic reactions, and taste disturbances.

Cineole (eucalyptol or 1,8-cineole) is an active molecule extracted from eucalyptus oil for use in medications, with possible antiinflammatory benefits, as well as effect on ciliary movement with increased beat frequency. It has been shown to augment the effectiveness of nasal decongestants for the treatment of acute rhinosinusitis compared with placebo, particularly when dosed early in the course of an infection. Mild side effects such as reflux, headache, and nausea have been reported from Cineole, but possible serious side effects from pure eucalyptus oil are well known. Undiluted eucalyptus oil is potentially very toxic, through both oral and topical dosing, and 3.5 mL of undiluted oil can be fatal. Signs of eucalyptus poisoning are dizziness, weakness, mydriasis, shortness of breath, and abdominal pain or burning.

Angelica ( Angelica archangelica ) or danngui is commonly used for upper respiratory illnesses, allergies, and coughs as an expectorant. Some inhibitory effect on prostaglandin E2 is seen, as well as inhibition of the cytochrome P450 pathway, although the mechanism of action is not known. Side effects like photosensitivity may occur.

Ephedra ( Ephedra sinica ) or ma huang contains high levels of ephedrine, and is often used for asthma, bronchitis, and nasal congestion, and as a weight loss aid and stimulant. The action of ephedrine can also lead to many serious side effects like tachycardia, palpitations, hallucinations, hypertension, paranoia, and potentially death, leading to a ban of ephedra in the United States. There are multiple interactions with drugs like glycosides and halothane causing arrhythmias and potentiation of monoamine oxidase inhibitors (MAOIs).

Licorice root ( Glycyrrhiza glabra ) is used in the treatment of allergic rhinitis, conjunctivitis, and bronchitis as an antiinflammatory, and antiviral activity has been noted on in vitro studies. Licorice is known to inhibit 11-β-hydroxysteroid dehydrogenase and the classic complement pathway, and side effects can include hypokalemia, muscle pain, extremity numbness, and pseudoaldosteronism, which leads to hypertension, headaches, and cardiac events. Risk for adverse events is higher with large doses, but can occur at low doses as well. Licorice also interferes with angiotensin-converting enzyme (ACE)–inhibitors, diuretics, corticosteroids, insulin and other diabetic drugs, MAOIs, oral contraceptives, and digoxin, where licorice can dangerously increase the toxicity of digoxin.

N -acetylcysteine (NAC) is used in the treatment of sinusitis primarily for its mucolytic properties, achieved through cleavage of disulfide bonds in mucoproteins by its sulfhydryl group resulting in less-viscous mucus. No serious side effects are known, but occasional gastrointestinal disturbances can occur. Adult dose is 600 to 1500 mg a day split into 8-hourly doses.

Ayurvedic Medicine

Ayurvedic medicine (from the Sanskrit ayur meaning life, and veda meaning science) is a traditional medical ideology originating in India with the goal of balancing the body, mind, and spirit through herbal medications, massage, and specific diets. More than 600 multiherb formulas and 250 single-herb medications are included in the Ayurvedic repertoire, including Aller-7 and Tinofend, which have been described for use in allergic rhinitis.

Aller-7 is a formulation of herbal extracts including quercetin, stinging nettles, methylsulfonylmethane, turmeric, feverfew, ginger, and vitamin C. It has shown some improvement in allergic rhinitis symptoms by possibly reducing inflammation.

Tinofend is a herbal tablet of Tinospora cordifolia that has shown efficacy compared with placebo; however, no studies have comprehensive data supporting the use of Aller-7 or Tinofend for allergic rhinitis.