Phleum pratense

Phleum pratense (Timothy Grass): A Comprehensive Reference

1. Identity and Botanical Classification

Phleum pratense L. is the accepted scientific binomial for the plant commonly known as timothy grass, meadow cat's tail, or, in French, fléole des prés or phléole des champs. Synonyms and common names in trade include Timothy, Timothy Grass, Mil, Fléole des Champs, and Fléole des Prés.

The species was first published in Species Plantarum (1753) and belongs to the family Poaceae. Its native range spans the Azores, Morocco, Europe to Siberia and the western Himalaya, and it grows primarily in the temperate biome as a perennial.

The genus Phleum comprises about 15 species widely distributed across temperate regions of the Northern and Southern Hemispheres; Phleum pratense is the most well-known species and is a popular forage crop for livestock.

Timothy grass is a cool-season perennial grass native to Europe, Asia, and North Africa. It typically grows to a height of 18–47 inches (45–120 cm), featuring slender, cylindrical stems. Its leaves are flat and narrow, with a prominent midrib. The inflorescence consists of dense, cylindrical seedheads containing tiny, wind-dispersed seeds.

Common Forms and Preparations

• The pollen from this plant is used as medicine. One preparation is administered sublingually to reduce symptoms of grass pollen allergies; a different preparation is injected subcutaneously to reduce symptoms of hay fever and other seasonal allergies.
• One of the most common traditional methods of using Phleum pratense is by brewing it as an herbal tea, steeping dried Timothy grass in hot water for about 10–15 minutes.
• Timothy grass is also available in various dietary supplement forms, such as capsules or tablets.
• An orodispersible grass allergen tablet (GRAZAX; ALK-Abelló) has been developed for sublingual administration; its active ingredient is a standardized allergen extract derived from the pollen of timothy grass (Phleum pratense).
• The grass SLIT tablet contains Phleum pratense grass pollen allergen extract and is formulated as a rapidly dissolving oral lyophilisate for sublingual administration.

2. Traditional and Historical Use

Timothy grass has a storied history extending beyond its widespread use as animal fodder. Traditionally, this hardy grass found a place in folk medicine, particularly in Europe and North America.

The use of Timothy grass can be traced back to ancient civilizations, where it was revered by traditional healers for its potential in treating various ailments, from digestive disorders to respiratory problems.

In Europe, Timothy grass gained popularity during the Middle Ages. Monks and herbalists incorporated it into their healing practices, and it was often prescribed to improve digestion and soothe skin irritations.

Native American tribes, such as the Iroquois, used Timothy grass for its medicinal benefits. It was employed to alleviate symptoms of coughs and colds. In the 19th century, Timothy grass found its way into medicinal literature as a remedy for respiratory conditions.

Historical herbalists valued its soothing qualities, often employing it as a mild remedy for urinary tract issues and to support kidney health. Infusions of the dried grass were sometimes used as a gentle diuretic. Additionally, the grass was occasionally included in poultices to ease skin irritations and minor wounds.

In the realm of herbal combinations, Phleum pratense was frequently combined with herbs like dandelion, nettle, and plantain to create teas or tonics aimed at supporting overall wellness, particularly renal and digestive health.

In traditional Chinese medicine, Phleum pratense has been used to treat coughs and bronchitis. In some cultures, the seeds of Phleum pratense were used as a source of food or made into a type of porridge.

It is important to note that traditional uses described above represent historical and ethnobotanical accounts and are not supported by controlled clinical evidence in most cases. They should be clearly distinguished from modern scientific evidence reviewed below.

3. Key Constituents and Active Compounds

Pollen Protein Profile and Allergens

The most scientifically studied constituents of Phleum pratense are found in its pollen grains, which have a complex biochemical composition.

Phleum pratense pollen grain (PPPG) contains about a hundred different proteins with molecular masses ranging from 10 to 94 kDa, with isoelectric points from 3.5–10.6. Among these proteins, allergens are classified in eleven groups from 1 to 13, with allergens from groups 1 and 5 being the major contributors to Phl p pollen allergy.

Databases Allergenonline.org and Allergen.org record ten P. pratense allergens and their isoforms. Phl p 1, Phl p 5, and Phl p 11 are major P. pratense-pollen allergens with demonstrated basophil activity and skin test reactivity.

Molecular and biochemical characterization of Phleum pratense has revealed several allergen components: rPhl p 1 and rPhl p 5 have been shown to be "species-specific allergens," while the profilin rPhl p 12 and the calcium-binding protein rPhl p 7 are the principal cross-reactive components.

Localization of major allergens Phl p 5 and Phl p 1 was visualized by electron microscopy and immunogold silver staining: Phl p 5 was found in the cytoplasm and on the exine, while Phl p 1 was found in the intine.

Major allergen Phl p 5 was quantified in pollen cytoplasmic granules by several studies, with concentration ranging from 2.7 to 3.5 μg/mg in unpolluted environments. Values for other allergens are scarce in the literature.

Lipids and Other Biochemicals

The extractable lipid fraction of pollen cytoplasmic granules is estimated between 1.7–2.2% of total pollen grain mass. The main chemical families of lipids reported include alkanes, alkenes, alcohols, saturated and unsaturated fatty acids, di- and tri-hydroxylated fatty acids, aldehydes, and sterols.

Pollen grains incubated in aqueous protein-free buffer solution were also found to secrete significant amounts of eicosanoids, namely prostaglandin E2 and leukotriene B4.

Polysaccharides and Other Bioactive Compounds

Some other biochemical characteristics such as NAD(P)H oxidase, protease activity, and pollen microbiome have been described in the literature. The bioaccessibility in physiological conditions has not been described for most biochemicals transported by allergenic pollen cytoplasmic granules. There is also a considerable lack of knowledge about the potential health effects of pollen constituents other than allergens.

Research suggests Phleum pratense contains bioactive compounds such as flavonoids and phenolic acids, which may contribute antioxidant and anti-inflammatory properties, though evidence for these effects in the context of dietary supplementation remains preliminary.

4. Mechanisms of Action

The principal and most rigorously documented mechanism of action of Phleum pratense preparations is allergen-specific immunomodulation. When administered as allergen immunotherapy (AIT), the mechanism involves multiple immunological pathways:

• IL-10 induction and regulatory T-cell activity: Following immunotherapy with Phleum pratense, local increases in IL-10 mRNA-positive cells were observed in the nasal mucosa after 2 years of immunotherapy (only during the pollen season), and IL-10 protein-positive cells were also increased. Following immunotherapy, peripheral T cells cultured in the presence of grass pollen extract also produced IL-10.
• IgG4 "blocking" antibody induction: Immunotherapy resulted in blunting of seasonal increases in serum allergen Phl p 5-specific IgE, 60- to 80-fold increases in Phl p 5-specific IgG, and 100-fold increases in Phl p 5-specific IgG4. Post-immunotherapy serum exhibited inhibitory activity which coeluted with IgG4 and blocked IgE-facilitated binding of allergen-IgE complexes to B cells. Both the increases in IgG and the IgG blocking activity correlated with the patients' overall assessment of improvement. Thus, grass pollen immunotherapy may induce allergen-specific, IL-10-dependent "protective" IgG4 responses.
• Th1/Th2 immune balance shifts: Phleum pratense sublingual immunotherapy in grass pollen allergic children modulates the immune response in the oral mucosa as well as systemically — by increasing Th1-responses, decreasing Th2-responses, and inducing immunoregulatory responses. Specifically, GRAZAX-treated children exhibited significantly higher levels of Phl p 1-specific salivary IgA and serum IgG4, along with significantly lower skin prick test positivity, after 3 years of treatment and 2 years after treatment cessation. Plasma levels of the Th1-associated chemokines CXCL10 and CXCL11 were significantly higher in treated children, and timothy-induced ratios of IL-5/IL-13 over IFN-γ were significantly decreased after 3 years of active treatment.
• Cross-reactive immunological protection: The levels of treatment-induced IgG4 detected by all grass species extracts displayed a clear correlation to that detected by the P. pratense pollen extract. T cell studies demonstrated cross-reactivity towards group 1 and 5 major allergens in extracts of six temperate grass species, and extensive T and B cell cross-reactivity was observed towards the allergens of the Pooideae grasses.
• T-cell epitope engagement: Fifteen T-cell epitopes could be identified on Phl p 1. Of 40 T-cell clones studied, 39 displayed the helper cell (Th) phenotype; specific stimulation induced a Th2-like type of cytokine production in 20 of 39 clones.

5. Scientific Evidence by Area of Use

5.1 Allergic Rhinoconjunctivitis (Hay Fever)

This is the most extensively studied application for Phleum pratense preparations. The evidence base is large, deriving from multiple randomized controlled trials (RCTs) and systematic reviews.

Sublingual immunotherapy (SLIT) tablets: Phase III trials investigated the efficacy and safety of three doses of grass allergen tablets in grass pollen–induced allergic rhinoconjunctivitis. The active ingredient is a standardized allergen extract derived from the pollen of timothy grass. Because of extensive cross-reactivity of allergenic components of grass pollens from different species, the clinical use of the grass allergen tablet is anticipated for IgE-mediated grass pollen allergy in general.

In one North American RCT, 439 adults with grass pollen-induced allergic rhinoconjunctivitis (ARC), with or without asthma, were randomized to once-daily 2,800 bioequivalent allergen units of standardized grass AIT (oral lyophilisate, Phleum pratense, 75,000 SQ-T, containing approximately 15 μg of Phl p 5) or placebo, approximately 16 weeks before the 2009 grass pollen season. Relative to placebo, grass AIT treatment improved total combined scores by 20% (p = .005), daily symptom scores by 18% (p = .02), and Rhinoconjunctivitis Quality of Life Questionnaire scores by 17% (p = .02).

Sublingual immunotherapy treatment with grass allergen tablets (Grazax) is initiated preseasonally without up-dosing and treatment is continued throughout the entire grass pollen season. Data from three randomized, double-blind, placebo-controlled, multi-centre trials with varying preseasonal treatment periods were analysed, based on data from 934 patients. Sublingual immunotherapy with Grazax must be initiated at least 8 weeks prior to the grass pollen season to provide significant clinical efficacy. A longer preseasonal treatment period (>8 weeks) improves clinical efficacy relative to placebo during the grass pollen season.

However, results have not been uniformly positive. In one Phase 3 trial, 289 subjects aged 18–65 were randomized 1:1 to once-daily 2800 BAU Timothy grass AIT (oral lyophilisate, Phleum pratense, 75,000 SQ-T, containing approximately 15 μg of Phl p 5) or placebo. Over the entire grass pollen season, mean daily symptom score was 6% lower with AIT versus placebo (5.69 vs. 6.06), but this difference was not statistically significant (p = 0.3475) despite significantly higher immunological response in the grass AIT group.

The Canadian Drug Expert Committee (CDEC) noted that the comparative clinical benefit of Phleum pratense allergenic extract (PPAE) is uncertain due to the variability of efficacy results across included RCTs and the small magnitude of absolute differences between PPAE and placebo. PPAE was statistically superior to placebo for daily medication score in four studies (GT-02, GT-08, GT-12, and P08067) and not statistically significantly different from placebo in four studies (GT-07, GT-14, P05238, and P05239).

Evidence strength: Moderate-to-strong for sublingual immunotherapy reducing hay fever symptom and medication scores, based on multiple RCTs, though absolute effect sizes are often modest and results across trials are variable.

5.2 Disease Modification and Long-Term Effects

A landmark NEJM study (Durham et al., 1999) demonstrated that immunotherapy for grass-pollen allergy for three to four years induces prolonged clinical remission accompanied by a persistent alteration in immunologic reactivity.

The main aim of specific immunotherapy is sustained effect due to changes in the immune system that can be demonstrated only in long-term trials. A 5-year double-blind, placebo-controlled trial — including 2 years of blinded follow-up after completion of a 3-year treatment period — investigated sustained efficacy and disease modification with the SQ-standardized grass allergy immunotherapy tablet, Grazax (Phleum pratense 75,000 SQ-T/2,800 BAU).

In the NEJM study, a standardized, aluminum hydroxide–adsorbed, depot grass-pollen vaccine (Alutard SQ) was used. Each monthly 1-ml maintenance injection contained 100,000 SQ units (containing 20 μg of the phleum allergen P5). For three years, 1-ml injections were given monthly in the upper arm, except during the pollen seasons when the maintenance dose was reduced by 40 percent.

Evidence strength: Strong for disease modification over 3–5 years of treatment, with evidence of persistent benefit 2–3 years after treatment cessation, based on phase III RCT data.

5.3 Asthma Prevention in Children

Some evidence suggests that giving Phleum pratense over a span of 3 years to children with grass allergy prevents development of asthma.

The GRAZAX Asthma Prevention (GAP) trial was a major multi-year study in this area. Eligible children were 5 to 12 years old at randomization, with a positive skin prick test and specific IgE to Phleum pratense (≥IgE class 2; ≥0.70 kU/L); grass allergic rhinoconjunctivitis requiring allergy pharmacotherapy during 2 grass pollen seasons prior to randomization; and no medical history of asthma and/or wheezing within the last 2 years or since the fifth birthday.

The benefits and safety of SQ timothy grass SLIT-tablet have been demonstrated in more than 900 actively treated children (n = 923 active; n = 895 placebo) in 9 completed clinical trials. The treatment period was up to 3 years in the phase 3 GAP and GT-23 trials, the longest trial duration ever in trials conducted with SLIT-tablets in children. Timothy grass SLIT-tablet is the most documented AIT product for the long-term treatment of allergic rhinoconjunctivitis in children and is approved for treatment in adults and children aged 5 years or older throughout Europe and North America.

Evidence strength: Moderate-to-strong for the possibility of reducing asthma risk in children with grass pollen allergy, based on phase III trial data; however, further independent confirmation and long-term follow-up data continue to be evaluated.

5.4 Local Allergic Rhinitis

A randomized double-blind placebo-controlled study evaluated the clinical efficacy and safety of Phleum pratense subcutaneous immunotherapy (Phl-SCIT) in local allergic rhinitis (LAR). 56 patients with moderate-severe LAR to grass pollen received Phl-SCIT with a depigmented polymerized pollen vaccine or placebo for the first year, and Phl-SCIT in the second year, with the blind maintained throughout. The primary outcome was the combined symptom medication score during grass pollen season.

Evidence strength: Preliminary in local allergic rhinitis, with limited controlled trial data available. This area warrants further investigation.

5.5 Intradermal Immunotherapy (Investigational Route)

In a double-blind, randomized, placebo-controlled trial of intradermal P. pratense allergoid immunotherapy, the dose of 0.06 μg of protein proved to be effective versus placebo by significantly reducing combined symptom-medication score and increasing tolerance to the allergenic extract in the conjunctival provocation test after the first pollen season. The treatment group also showed a significant reduction in specific IgE after the second pollen season relative to baseline.

However, caution is warranted. A separate trial of intradermal grass pollen immunotherapy found negative outcomes: There was no significant difference in the primary endpoint between treatment arms. Among secondary endpoints, nasal symptoms were significantly worse in the intradermal treatment group. In a per-protocol analysis, intradermal immunotherapy was further associated with worse asthma symptoms and fewer symptom-free days. Intradermal immunotherapy increased serum Phleum pratense-specific IgE levels (p = 0.001) compared with the control arm.

Evidence strength: Conflicting; intradermal route cannot currently be recommended based on the available evidence, with at least one well-designed trial showing worsening of symptoms.

5.6 Antioxidant and Anti-inflammatory Properties (Preclinical)

While studies on direct nutritional supplementation are limited, flavonoids and phenolic acids in Phleum pratense are generally recognized for their potential health-promoting effects. The use of Phleum pratense in nutritional products is often based on these promising bioactive components, although robust clinical evidence confirming their efficacy in broader health contexts is still emerging.

Evidence strength: Preclinical and theoretical only. No controlled human trials are currently available supporting the use of Phleum pratense specifically for antioxidant or anti-inflammatory benefits in humans outside the allergen immunotherapy context.

6. Body Systems and Health Areas

• Respiratory/Immunological System: The primary and best-documented area of use. Grass pollen allergy (hay fever) is the principal indication. Specific preparations of Phleum pratense seem to significantly reduce hay fever symptoms in people with asthma. The injectable form may also reduce asthma symptoms.
• Immune System Modulation: In recent years, Phleum pratense has garnered attention for its potential use in nutritional products, particularly in the context of allergy management and immune health.
• Skin: In some traditional remedies, Timothy grass is used topically, applied as a poultice or in the form of a salve to soothe skin irritations or muscle discomfort. No clinical trial evidence supports this use.
• Digestive and Urinary Systems (Traditional): Historically, it was frequently combined with other herbs to create teas or tonics aimed at supporting overall wellness, particularly renal and digestive health. No clinical trial evidence supports these uses.

7. Dosage Forms and Doses Reported in Studies

The following dosages have been reported in peer-reviewed clinical studies or official product information. These figures are drawn directly from study sources and should not be construed as prescriptive.

• Sublingual tablet (GRAZAX/GRASTEK), allergic rhinoconjunctivitis in adults: 75,000 SQ-T units of a specific standardized Phleum pratense allergen product (Grazax, ALK Abelló) daily, starting 8 weeks before grass pollen season and continued until it ends.
• Sublingual tablet, North American adult ARC trials: Once-daily 2,800 bioequivalent allergen units of standardized grass AIT (oral lyophilisate, Phleum pratense, 75,000 SQ-T, containing approximately 15 μg of Phl p 5), administered approximately 16 weeks before the grass pollen season.
• Sublingual tablet, Canadian adult and pediatric trials: 2800 BAU SLIT-T once daily. Subjects were treated for approximately 12 or 16 weeks before the grass pollen season and through the entire grass pollen season, for a total of ≥23 weeks post-randomization. The grass SLIT-T does not require up-titration, as the first dose is considered the maintenance dose.
• Official recommended dose (GRAZAX product information): The recommended dose is one sublingual tablet (75,000 SQ-T) daily. It is recommended that the first sublingual tablet is taken under medical supervision and that the patient is monitored for 30 minutes.
• Subcutaneous depot injection, Durham NEJM long-term study: Each monthly 1-ml maintenance injection contained 100,000 SQ units (equivalent to 10,000 biologic units and containing 20 μg of the phleum allergen P5). For three years, 1-ml injections were given monthly in the upper arm, except during the pollen seasons, when the maintenance dose was reduced by 40 percent.
• Sublingual liquid drops (SUBLIVAC Phleum): Subjects started with one drop and one drop was added each consecutive day until the maintenance dose of 5 drops per day was reached. Treatment at maintenance dose was then continued for 10 months.
• Intradermal allergoid (investigational): A multicenter trial in patients aged 12–65 years divided subjects into three groups receiving a total of six doses at weekly intervals of either placebo, 0.03, or 0.06 μg of protein per dose of P. pratense allergoid.
• Pediatric GAP trial: The daily dose is 1 tablet, for at-home administration, except the first intake which was taken under medical supervision.

8. Safety Considerations and Known Adverse Effects

General Safety Profile

Phleum pratense seems safe for most adults and children aged 3–16 years.

Local and Systemic Adverse Events (SLIT)

When used under the tongue, Phleum pratense can cause itching and irritation of the mouth and nose, blisters in the mouth, and runny nose. When given by injection, it can cause irritation where the needle entered the skin.

Pooled data from pediatric clinical trials indicate that short- and long-term timothy grass SLIT-tablet is well tolerated in children, regardless of geographic region. Adverse events were generally local, mild, and transient allergic reactions.

The most frequently reported adverse events with Phleum pratense allergenic extract (PPAE) were those associated with the mouth or throat. Serious adverse events and withdrawals due to adverse events were few and similar in both groups across trials.

Grazax grass allergen tablets are well tolerated in patients with grass pollen allergy, with most adverse events being mild local reactions. There have been no instances of anaphylaxis.

Pregnancy and Lactation

Treatment with GRAZAX should not be initiated during pregnancy. If pregnancy occurs during treatment, treatment may continue after evaluation of the general condition (including lung function) of the patient. No clinical data are available for the use of GRAZAX during lactation.

The effects of timothy grass (Phleum pratense) pollen allergen extract on embryo-fetal development were evaluated in mice. No adverse effects on embryo-fetal development were observed following oral dosing at up to approximately 1,522 times the human clinical dose during the period of organogenesis.

Initiation of allergy immunotherapy while breastfeeding is not recommended.

Contraindications and Drug Interactions

Other chronic or immunological disease that could interfere with the assessment of the investigation product or that could generate any additional risk for the patient has been used as an exclusion criterion in clinical trials.

Patients under treatment with tricyclic antidepressants, psychotropics, or beta-blockers have been excluded from SCIT trials, reflecting practitioner-level caution about co-administration of these agents with allergen immunotherapy.

Patients with severe asthma or forced expiratory volume in 1 second (FEV1) less than 70% — even if pharmacologically controlled — have been excluded from SCIT studies.

A previous history of anaphylaxis and chronic urticaria have also been used as exclusion criteria in SCIT research settings.

Risks of Inappropriate Administration Route

Desensitization by subcutaneous injection has been shown to be very efficacious; however, a rare side effect of desensitizing injections is anaphylaxis, and so use is limited to specialized centers.

As noted above, intradermal immunotherapy (a non-approved investigational approach) has been associated with paradoxical worsening: Nasal symptoms were significantly worse in the intradermal treatment group. In a per-protocol analysis, intradermal immunotherapy was further associated with worse asthma symptoms and fewer symptom-free days, and it increased serum Phleum pratense-specific IgE levels.

Evidence Limitations for Non-Immunotherapy Uses

The use of Phleum pratense in nutritional products is often based on promising bioactive components, although robust clinical evidence confirming their efficacy in broader health contexts is still emerging. While more research is needed to fully establish the wide-ranging benefits of Phleum pratense in nutrition, its historical use and positive outcomes observed in allergy treatment provide a foundation for its inclusion in health-oriented products.

References

• Plants of the World Online — Phleum pratense L. (Kew Science)
• Visez N et al. Biochemical composition of Phleum pratense pollen grains: A review. Mol Immunol. 2021;136:98-109. (PubMed)
• Phleum pratense-pollen adaptive variations and pollen microbiome investigation under different climatic regions. (PubMed)
• Detection of Phl p 1, Phl p 5, Phl p 7 and Phl p 12 specific IgE antibodies in Phleum-allergic patients. (PubMed)
• Sensitization to timothy grass pollen allergenic molecules in children. (PMC)
• Timothy grass (Phleum pratense L.) pollen as allergen carriers and initiators of an allergic response. (PubMed)
• T-cell epitopes of Phl p 1, major pollen allergen of timothy grass. (PubMed)
• Grass pollen immunotherapy induces mucosal and peripheral IL-10 responses and blocking IgG activity. (PubMed)
• Sublingual immunotherapy alters salivary IgA and systemic immune mediators in timothy allergic children. (PubMed)
• Phleum pratense alone is sufficient for allergen-specific immunotherapy against allergy to Pooideae grass pollens. (PubMed)
• Immunotherapy with a Phleum pratense allergen extract induces an immune response to a grass-mix allergen extract. (PubMed)
• Efficacy and safety of timothy grass allergy immunotherapy tablet treatment in North American adults. (PubMed)
• Durham SR et al. Sublingual immunotherapy with once-daily grass allergen tablets: A randomized controlled trial. J Allergy Clin Immunol. 2006. (JACI)
• Prolonged preseasonal treatment phase with Grazax sublingual immunotherapy increases clinical efficacy. (PubMed)
• Durham SR et al. Long-term clinical efficacy of grass-pollen immunotherapy. N Engl J Med. 1999;341:468–475. (NEJM)
• The efficacy and safety of the Timothy grass allergy sublingual immunotherapy tablet in Canadian adults and children. (PMC)
• Critical appraisal of Timothy grass pollen extract GRAZAX® in the management of allergic rhinitis. (PMC)
• A phase 3 trial assessing the efficacy and safety of grass allergy immunotherapy tablet in subjects with grass pollen-induced allergic rhinitis. (PMC)
• Safety of Timothy Grass Sublingual Immunotherapy Tablet in Children: Pooled Analyses of Clinical Trials. (PubMed)
• Results from the 5-year SQ grass SLIT tablet asthma prevention (GAP) trial in children. (JACI)
• Safety of Timothy Grass Sublingual Immunotherapy Tablet in Children: Pooled Analyses of Clinical Trials. (ScienceDirect)
• Intradermal Phleum pratense allergoid immunotherapy. Double-blind, randomized, placebo-controlled trial. (PubMed)
• Intradermal grass pollen immunotherapy increases TH2 and IgE responses and worsens respiratory allergic symptoms. (PubMed)
• Specific immunotherapy in local allergic rhinitis: A randomized, double-blind placebo-controlled trial with Phleum pratense subcutaneous allergen immunotherapy. (PubMed)
• Durham SR et al. SQ-standardized sublingual grass immunotherapy: Confirmation of disease modification 2 years after 3 years of treatment. (ScienceDirect)
• An extract of Timothy-grass pollen used as sublingual immunotherapy for summer hay fever. (PubMed)
• CDEC Final Recommendation — Standardized Allergenic Extract, Timothy grass (Phleum pratense) (GRASTEK). (NCBI Bookshelf)
• GRAZAX® (Phleum pratense) Australian Product Information (Seqirus)
• Phleum Pratense: Health Benefits, Side Effects, Uses, Dose & Precautions (RxList)
• Phleum Pratense — an overview (ScienceDirect Topics)
• Sublingual immunotherapy: World Allergy Organization position paper 2013 update. (PMC)