Hyssop

The part used is the flowering top and leaf, gathered as the spikes open and dried for infusion. Western herbalists treat hyssop as a warm, aromatic, slightly bitter herb.

It is given as an expectorant for cough, cold and bronchial congestion, as a carminative for sluggish digestion and wind, and as a diaphoretic to bring on a sweat in fever. The respiratory use comes first.

Hyssop has been grown in European monastery and physic gardens for centuries. Its name traces to the Hebrew ezob, a plant of the Bible, though the link is thought to rest on a misreading ^{27Reference 27Nurzyńska-Wierdak R · 2026ReviewOntogenetic and Environmental Variability of Hyssop (Hyssopus officinalis L.) Essential Oil Composition and Activity — [review]View study →}.

Classical Persian medical texts recommend hyssop for asthma ^{1Reference 1Daneshfard B et al. · 2024RCTEffect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma — [randomised double-blind placebo-controlled trial]View study →}.

In the Uyghur medicine of Xinjiang, hyssop is an established herb for asthma and airway complaints ^{2,3,4Reference 2Ma X et al. · 2014AnimalEffect of Hyssopus officinalis L. on inhibiting airway inflammation and immune regulation in a chronic asthmatic mouse model — [mouse model — in vivo]View study →Reference 3Ma X et al. · 2014AnimalThe Effects of Uygur Herb Hyssopus officinalis L. on the Process of Airway Remodeling in Asthmatic Mice — [mouse model — in vivo]View study →Reference 4Wang HY et al. · 2011AnimalThe effect of Uygur medicine Hyssopus officinalis L. on expression of T-bet, GATA-3 and STAT-3 mRNA in lung tissue of asthma rats — [rat model — in vivo]View study →}.

A 2024 randomised, triple-blind, placebo-controlled trial gave 60 patients with mild-to-moderate asthma either hyssop syrup or a plain sugar syrup, 5 mL twice daily for four weeks, alongside their usual treatment ^{1Reference 1Daneshfard B et al. · 2024RCTEffect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma — [randomised double-blind placebo-controlled trial]View study →}. Patients with a productive cough improved on FEV1, the Asthma Control Test, peak expiratory flow, MEF25–75% and wheezing severity. Patients with a dry cough got worse on the same measures ^{1Reference 1Daneshfard B et al. · 2024RCTEffect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma — [randomised double-blind placebo-controlled trial]View study →}.

The authors concluded that the syrup suits asthmatic patients with a productive cough and is not suitable for those with a dry cough ^{1Reference 1Daneshfard B et al. · 2024RCTEffect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma — [randomised double-blind placebo-controlled trial]View study →}.

Three rodent studies of ovalbumin-induced asthma, using hyssop as a Uyghur medicine, found that extracts reduced eosinophils in the airways and brought serum IgE and IgG back to normal ^{2Reference 2Ma X et al. · 2014AnimalEffect of Hyssopus officinalis L. on inhibiting airway inflammation and immune regulation in a chronic asthmatic mouse model — [mouse model — in vivo]View study →}. They also lowered MMP-9 and TIMP-1 expression with less airway remodelling ^{3Reference 3Ma X et al. · 2014AnimalThe Effects of Uygur Herb Hyssopus officinalis L. on the Process of Airway Remodeling in Asthmatic Mice — [mouse model — in vivo]View study →}, and shifted T-bet, GATA-3 and STAT-3 expression away from a Th2-type allergic profile ^{4Reference 4Wang HY et al. · 2011AnimalThe effect of Uygur medicine Hyssopus officinalis L. on expression of T-bet, GATA-3 and STAT-3 mRNA in lung tissue of asthma rats — [rat model — in vivo]View study →}.

Gap: a single small RCT with a subgroup-dependent result; the animal work uses a specific Uyghur-medicine extract, and none of it tests the tea or dried herb at ordinary doses.

Antioxidant activity is hyssop’s most-replicated in vitro property, and it comes from the phenolic acids and flavonoids rather than the oil. Ethanolic and aqueous extracts scavenge DPPH radicals and show ferric-reducing (FRAP) and Trolox-equivalent capacity, with the activity tracking rosmarinic acid, chlorogenic acid, caffeic acid and free luteolin ^{5,7,8Reference 5Vlase L et al. · 2014In vitroEvaluation of antioxidant and antimicrobial activities and phenolic profile for Hyssopus officinalis, Ocimum basilicum and Teucrium chamaedrys — [in vitro]View study →Reference 7Michalak M et al. · 2024In vitroPhytochemical Profile and Antioxidant and Protective Activities of Various Types of Extracts from Hyssopus officinalis L. and Grindelia robusta Nutt. — [in vitro]View study →Reference 8Fathiazad F et al. · 2011In vitroPhytochemical analysis and antioxidant activity of Hyssopus officinalis L. from Iran — [in vitro]View study →}.

Methanol extracts of subsp. aristatus showed moderate-to-weak antioxidant activity (DPPH IC50 56–200 µg/mL) ^{6Reference 6Mićović T et al. · 2021In vitroAntioxidant, Antigenotoxic and Cytotoxic Activity of Essential Oils and Methanol Extracts of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae) — [in vitro]View study →}.

The work is all in vitro, with no cellular or human endpoint.

Two α-glucosidase-inhibiting compounds, both syringoylglycerol glucosides, were isolated and characterised from dried hyssop leaves ^{11Reference 11Matsuura H et al. · 2004In vitroIsolation of alpha-glucosidase inhibitors from hyssop (Hyssopus officinalis) — [in vitro — constituent isolation]View study →}.

In the rat everted gut sac, hyssop extract inhibited the digestion of sucrose and maltose but left pure-glucose absorption unaffected. In mice loaded with sucrose or maltose, oral extract at 300 and 100 mg/kg respectively blunted the rise in blood sugar within 30–60 minutes ^{12Reference 12Miyazaki H et al. · 2003AnimalInhibitory effects of hyssop (Hyssopus officinalis) extracts on intestinal alpha-glucosidase activity and postprandial hyperglycemia — [animal model — in vivo (rat, mouse)]View study →}. The extract slows the breakdown of complex carbohydrates rather than glucose uptake.

In streptozotocin-diabetic rats, a 500 mg/kg alcoholic extract given for one month lowered GSK-3β, C-fos, NF-κB and TNF-α gene expression and raised expression of the cholesterol transporters ABCA1 and ABCG1 ^{13Reference 13Abdel-Megeed RM et al. · 2020AnimalHyssopus officinalis exerts hypoglycemic effects on streptozotocin-induced diabetic rats via modulating GSK-3β, C-fos, NF-κB, ABCA1 and ABCG1 gene expression — [rat model — in vivo]View study →}.

All of it is preclinical. There is no human glycaemic data and no dose-finding, and the effect belongs to methanol and ethanol leaf extracts rather than to culinary amounts.

One study carries this indication across three levels of evidence. Methanol extracts of hyssop herb inhibited COX-2 by 54–63% at 20 µg/mL, comparable to celecoxib (61.6%), while the essential oil showed no significant activity ^{9Reference 9Mićović T et al. · 2022In vitroIn vitro, in vivo and in silico evaluation of the anti-inflammatory potential of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae) — [in vitro, in vivo (rat) and in silico]View study →}.

The same extracts reduced carrageenan-induced paw edema in rats at 200 mg/kg, comparably to or better than indomethacin, and molecular docking pointed to chlorogenic and rosmarinic acid binding the COX enzymes ^{9Reference 9Mićović T et al. · 2022In vitroIn vitro, in vivo and in silico evaluation of the anti-inflammatory potential of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae) — [in vitro, in vivo (rat) and in silico]View study →}. The airway-inflammation models ^{2,4Reference 2Ma X et al. · 2014AnimalEffect of Hyssopus officinalis L. on inhibiting airway inflammation and immune regulation in a chronic asthmatic mouse model — [mouse model — in vivo]View study →Reference 4Wang HY et al. · 2011AnimalThe effect of Uygur medicine Hyssopus officinalis L. on expression of T-bet, GATA-3 and STAT-3 mRNA in lung tissue of asthma rats — [rat model — in vivo]View study →} point the same way.

Gap: one primary study; no human anti-inflammatory data; the active preparation is the phenolic extract, not the oil or the whole herb.

Ethanolic extracts of hyssop were tested for antimicrobial activity by disk diffusion alongside basil and wall germander, and germander was the most active of the three ^{5Reference 5Vlase L et al. · 2014In vitroEvaluation of antioxidant and antimicrobial activities and phenolic profile for Hyssopus officinalis, Ocimum basilicum and Teucrium chamaedrys — [in vitro]View study →}.

Hyssop essential oil was not active against Helicobacter pylori at the highest concentration tested ^{10Reference 10Knezevic P et al. · 2018In vitroA colorimetric broth microdilution method for assessment of Helicobacter pylori sensitivity to antimicrobial agents — [in vitro]View study →}. A 2026 review describes the oil’s antibacterial activity as moderate or weak, and lower than that of standard antibiotics and antifungals ^{27Reference 27Nurzyńska-Wierdak R · 2026ReviewOntogenetic and Environmental Variability of Hyssop (Hyssopus officinalis L.) Essential Oil Composition and Activity — [review]View study →}.

All of it is in vitro.

Hyssop’s carminative and antispasmodic reputation has one direct study. In isolated guinea-pig ileum, the essential oil and its component isopinocamphone inhibited acetylcholine-induced contractions (IC50 42 and 62 µg/mL) and barium chloride-induced contractions (IC50 48 and 70 µg/mL). Limonene and beta-pinene had no effect ^{14Reference 14Lu M et al. · 2002Muscle relaxing activity of Hyssopus officinalis essential oil on isolated intestinal preparations — [ex vivo (isolated guinea-pig ileum)]View study →}.

The oil also blocked calcium chloride-induced contraction. In rabbit jejunum it reduced spontaneous movement and basal tone, and blockers of the nitric oxide and β-adrenergic pathways did not prevent the effect ^{14Reference 14Lu M et al. · 2002Muscle relaxing activity of Hyssopus officinalis essential oil on isolated intestinal preparations — [ex vivo (isolated guinea-pig ileum)]View study →}.

The active material was the essential oil, the same fraction that carries the convulsant ketones.

Gap: ex vivo only, and the active preparation is the oil, which is not taken internally; no study shows the tea reproduces this.

One rodent study supports a gastroprotective effect. An ethanolic leaf extract (250 and 500 mg/kg for 10 days) reduced the ulcer index and lipid peroxidation (TBARS) and raised mucus, SOD, GSH and catalase in rats given indomethacin, with histology confirming mucosal protection. The effect was comparable to ranitidine ^{15Reference 15Tahir M et al. · 2022AnimalGastroprotective effect of Hyssopus officinalis L. leaves via reduction of oxidative stress in indomethacin-induced gastric ulcer in experimental rats — [rat model — in vivo]View study →}.

It is a single animal study with no human data.

Methanol extracts reduced viability and induced apoptosis in C6 glioma cells. In rats with implanted C6 glioma, 100 mg/kg for seven days reduced tumour volume and prolonged survival ^{19Reference 19Khaksar S et al. · 2022In vitroThe Effects of Methanol Extracts of Hyssopus officinalis on Model of Induced Glioblastoma Multiforme (GBM) in Rats — [in vitro and rat model — in vivo]View study →}.

Callus-culture extracts containing rosmarinic acid reduced the viability of MCF-7 breast-cancer cells ^{20Reference 20Yahia Darwish H et al. · 2020In vitroInduction of Biosynthetic Genes Related to Rosmarinic Acid in Plant Callus Culture and Antiproliferative Activity Against Breast Cancer Cell Line — [in vitro (cell line)]View study →}.

Methanol extracts of subsp. aristatus were tested against SW480, MDA-MB-231 and HeLa cells and were selectively and potently active against HeLa ^{6Reference 6Mićović T et al. · 2021In vitroAntioxidant, Antigenotoxic and Cytotoxic Activity of Essential Oils and Methanol Extracts of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae) — [in vitro]View study →}.

The work is cell-line studies and one rat model, with no pharmacokinetic or human data.

In 1990, crude extracts of dried leaves inhibited HIV-1 replication in vitro (syncytia formation, reverse transcriptase, p17/p24) without harming uninfected cells ^{16Reference 16Kreis W et al. · 1990In vitroInhibition of HIV replication by Hyssop officinalis extracts — [in vitro]View study →}. The authors identified caffeic acid in the active extract, found it active on its own, and suggested that unidentified tannins also contribute ^{16Reference 16Kreis W et al. · 1990In vitroInhibition of HIV replication by Hyssop officinalis extracts — [in vitro]View study →}.

In 1995 a polysaccharide (MAR-10) isolated from the aqueous extract inhibited HIV-1 replication in a concentration-dependent way and showed broad anti-glycosidase activity ^{17Reference 17Gollapudi S et al. · 1995In vitroIsolation of a previously unidentified polysaccharide (MAR-10) from Hyssop officinalis that exhibits strong activity against human immunodeficiency virus type 1 — [in vitro]View study →}.

A 2022 study found that hyssop extract raised expression of the endosomal Toll-like receptors (TLR3/7/8/9), MyD88 and NF-κB in human blood cells and increased interferon-α and -β release, suggesting an innate antiviral immune response ^{18Reference 18Ghasempour M et al. · 2022In vitroThe impact of Hyssop (Hyssopus officinalis) extract on activation of endosomal toll-like receptors and their downstream signaling pathways — [in vitro (human PBMC)]View study →}.

Gap: the direct anti-HIV work is 30+ years old, in vitro, and never advanced; the TLR study is a single cell-based report. No clinical antiviral evidence.

The leaf and tea. Used as a culinary herb or a mild tea, hyssop has a long record of use, and no serious adverse effects are reported at those amounts.

The essential oil. Commercial hyssop oils have caused tonic-clonic seizures in people ^{22,23Reference 22Millet Y et al. · 1981Case reportToxicity of some essential plant oilsView study →Reference 23Burkhard PR et al. · 1999Case reportPlant-induced seizures: reappearance of an old problem — [case reports]View study →}. In rats, hyssop oil caused convulsions above 0.13 g/kg and was lethal above 1.25 g/kg, making it more convulsant than sage oil, and repeated small doses had a cumulative effect ^{21,22Reference 21Millet Y et al. · 1979AnimalExperimental study of the toxic convulsant properties of commercial preparations of essences of sage and hyssop — [animal model — experimental (rat)]View study →Reference 22Millet Y et al. · 1981Case reportToxicity of some essential plant oilsView study →}. The oil’s ketones, pinocamphone and isopinocamphone, block the GABA-A receptor ^{24Reference 24Höld KM et al. · 2002In vitroMetabolism and mode of action of cis- and trans-3-pinanones (the active ingredients of hyssop oil) — [in vitro — mechanistic (liver microsomes, CYP3A4)]View study →}. The water infusion carries far less of these ketones than the distilled oil.

Seizure disorders, pregnancy and children. Because the ketones act on the GABA system, the oil and high doses of the herb are avoided by anyone with epilepsy or a seizure disorder, in pregnancy, and in young children ^{25Reference 25Bahr TA et al. · 2019Systematic reviewThe Effects of Various Essential Oils on Epilepsy and Acute Seizure: A Systematic Review — [systematic review]View study →}.

Methyleugenol. Some hyssop chemotypes contain up to 28% methyleugenol in the oil ^{6Reference 6Mićović T et al. · 2021In vitroAntioxidant, Antigenotoxic and Cytotoxic Activity of Essential Oils and Methanol Extracts of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman (Lamiaceae) — [in vitro]View study →}. The European Medicines Agency’s herbal committee describes methyleugenol as a naturally occurring genotoxic carcinogen ^{30Reference 30Committee on Herbal Medicinal Products ( · 2005Final public statement on the use of herbal medicinal products containing methyleugenol (EMEA/HMPC/138363/2005) — regulatory statementView study →}.

Chemotype. Oil composition varies widely with chemotype, growing conditions and stage of growth, so the ketone content of a given oil cannot be assumed from the species name ^{27Reference 27Nurzyńska-Wierdak R · 2026ReviewOntogenetic and Environmental Variability of Hyssop (Hyssopus officinalis L.) Essential Oil Composition and Activity — [review]View study →}.

Allergy. Cross-sensitivity between mint-family herbs has been documented ^{26Reference 26Benito M et al. · 1996Case reportLabiatae allergy: systemic reactions due to ingestion of oregano and thyme — [case reports]View study →}.

Interactions. The oil’s ketones (cis- and trans-3-pinanone) are metabolised by human CYP3A4 ^{24Reference 24Höld KM et al. · 2002In vitroMetabolism and mode of action of cis- and trans-3-pinanones (the active ingredients of hyssop oil) — [in vitro — mechanistic (liver microsomes, CYP3A4)]View study →}. No clinical herb–drug interaction has been studied.