Basil vs. Thai Basil: Flavor, Uses and Swaps

Thai basil is not a separate species. It is a cultivated form of sweet basil, Ocimum basilicum, the same plant as the Italian basil in pesto.¹² What separates them in the kitchen is smell and leaf: Thai basil’s oil leans hard toward anise, and its sturdier leaves are usually wilted into hot stir-fries and curries or eaten raw beside noodle soup, while Italian basil is the softer, sweeter herb of tomato sauces and pesto.³⁴

Side by side

	Basil (sweet or Italian basil)	Thai basil
Species	Ocimum basilicum⁵	Ocimum basilicum; often labeled var. thyrsiflora or thyrsiflorum, a name Kew treats as a synonym of ordinary sweet basil¹²
Family	Lamiaceae (mint family)⁵	Lamiaceae (mint family)⁵
Native range of the species	Tropical and subtropical Asia to northern Australia⁵	Same species; where the Thai type was selected is not documented in any source we found
Part used	Leaves, fresh or dried²	Fresh leaves and flowering tops
Leading aroma compounds	Methyl chavicol (estragole) and linalool, in proportions that vary by type²⁶	Estragole, then geranial and neral, in one Thai study³
Flavor (editorial)	Sweet and green, with a peppery edge and a hint of clove	Stronger, with pronounced anise or licorice and a peppery bite
Forms sold	Fresh, dried, ground dried	Mostly fresh
Typical uses	Italian pizza, pasta and pesto; French omelets and soups⁶	Thai stir-fries and green curry; raw on the Vietnamese pho herb plate⁷⁴
Safety	Estragole, assessed by EU and German regulators (see below)⁸⁹	Same compound, same assessments; neither regulator singles out Thai basil⁸⁹
Price	No dated, sourced retail comparison found	No dated, sourced retail comparison found

The flavor row is our description. The anise half of it is backed by chemistry: in a 2018 study of basils used as food in Thailand, Thai basil’s oil was linked to anise, lime-like and fresh aromas.³ For each herb in depth, see the basil and Thai basil profiles.

How to tell them apart

Britannica describes sweet basil leaves as glossy and oval, with smooth or slightly toothed edges that typically cup a little, set opposite each other on square stems.² Across the species, PROSEA records stems from light green to dark purple and flowers that are whitish-purplish, white or creamy yellow, so color alone does not settle which basil you have.⁶ What PROSEA gives as the mark of var. thyrsiflorum is the flower head: densely branched, with loose whorls of flowers.⁶

In Thai, PROSEA gives horapha as the name for sweet basil, the species.⁶ Purple stems are often taken as the sign of Thai basil, but Andy Ricker warns that the label “holy basil” is sometimes put on purple-stemmed Thai or sweet basil, so the stem color is not a guarantee of anything either.¹⁰ Holy basil (kaphrao) is a different species again; see Thai basil vs. holy basil.

The difference in the oil

Both herbs share estragole (also called methyl chavicol) as a leading compound.⁶³ What changes is what sits beside it. The figures below come from different studies, measured different ways, so they show which compounds lead in each sample, not how much stronger one herb is than the other.

Sample (scope)	Estragole / methyl chavicol	Other main compounds	Units	Source
Thai basil, fresh leaves grown at a Chiang Mai research center, hydrodistilled	452.80	Geranial 180.57, neral 151.16	µg/mL of oil	Tangpao et al. 2018³
“French basil” oil distilled in the Philippines	53.3%	Linalool 22.0%, eugenol 1.4%	% of oil	PROSEA⁶
Sweet basil oil, range in the EU assessment	20 to 43%	not given	% of oil	EU Scientific Committee on Food⁸

The Thai study linked its Thai basil oil to anise, lime-like and fresh aromas, while PROSEA describes French-type basil oil as sweet-spicy, slightly green and fresh.⁶³ PROSEA recognizes at least six chemical types within O. basilicum, so any one basil plant may sit closer to or farther from these samples.⁶

Differences that change the dish

When it goes in. LSU AgCenter groups basil with the delicate herbs best added a minute or two before cooking ends, because long heat costs flavor and aroma.¹¹ That fits Italian basil well. For Thai basil, Sherri Pengjad of Thai Foodie says it is sturdier and holds up much better in hot dishes, and she stirs it into green curry right before serving.⁴ Either way, the common practice is late, not early. No source we found tests how long either herb survives a simmer.

Raw on the plate. In Vietnamese cooking, Thai basil is one of the raw herbs served with pho. Andrea Nguyen lists it on her garnish plate with mint and other herbs, adds it when it is in season, and tells readers to add or subtract herbs as they like.⁷ So it is a welcome pho garnish, not a required one.

In pesto and Italian cooking. PROSEA names pizzas, pasta, chicken and cheese dishes, and pesto as the Italian uses of sweet basil.⁶ Thai basil’s anise would change a pesto noticeably; that is our judgment, not a tested result.

Can one stand in for the other?

Yes, with a flavor shift you can predict. Both directions are covered in more detail on Thai basil substitutes, and the amounts below follow that page’s treatments.

Italian basil for Thai basil: same amount (Attributed). Nagi Maehashi of RecipeTin Eats calls normal basil the best substitute for Thai basil, while noting that it lacks Thai basil’s slight aniseed flavor.¹² Pengjad also names Italian basil as the best substitute.⁴ Pailin Chongchitnant’s pad kra pao recipe lists holy basil or regular basil in the same 1 1/4 cups and notes that Thai basil will also work, which treats the basils as interchangeable by volume.¹³ Add it at the very end and stir only until it wilts.
To get closer to Thai basil (Method). Pengjad suggests mixing Italian basil with a little mint, without giving amounts.⁴ No published ratio exists; start with about four parts basil to one part mint, in the same total amount, and taste.
Thai basil for Italian basil (Method). We found no source that publishes this swap or a ratio for it. In cooked tomato sauces it works if you accept a licorice note; start with a little less than the recipe’s basil and taste. For pesto, Caprese-style salads and other raw uses, the anise is front and center, so we would not swap.

Holy basil is not a stand-in for either in this comparison’s sense: it is a different species with a peppery, spice-like profile, and it is the herb that gives phat kaphrao its name.³¹⁰

What isn’t known

No study we found compares Thai and Italian basil grown and analyzed the same way. The oil figures above come from separate studies with different units.
No source documents where or when the Thai type of sweet basil was selected.
The claim that Thai basil tolerates long cooking better than Italian basil is a cook’s observation; no test was found.
No published ratio exists for using Thai basil in place of Italian basil.

Safety

Estragole, a leading compound in both herbs, is the safety question regulators have examined. In 2001 the EU Scientific Committee on Food concluded that estragole is genotoxic and carcinogenic, based mainly on studies in mice dosed orally, and could not set a safe exposure limit.⁸ In 2022 Germany’s BfR said the risk from estragole and related compounds in food cannot yet be conclusively assessed; it named basil-containing pesto among foods that may contain high amounts and made no consumption recommendation for consumers.⁹ Neither body tells people to stop eating basil, and neither singles out Thai basil.

Ocimum thyrsiflorum L. (synonym of O. basilicum var. basilicum), Plants of the World Online, Royal Botanic Gardens, Kew. powo.science.kew.org · Reference work ↩ ↩²
“Basil”, Encyclopaedia Britannica, 2026. britannica.com · Reference work ↩ ↩² ↩³ ↩⁴ ↩⁵
Tangpao, Chung and Sommano, “Aromatic Profiles of Essential Oils from Five Commonly Used Thai Basils”, Foods, 2018. mdpi.com · Peer-reviewed ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷
Sherri Pengjad, “Thai Basil: What It Is and How to Use It”, Thai Foodie, 2026. thai-foodie.com · Publication ↩ ↩² ↩³ ↩⁴ ↩⁵
Ocimum basilicum L., Plants of the World Online, Royal Botanic Gardens, Kew. powo.science.kew.org · Reference work ↩ ↩² ↩³ ↩⁴
N.O. Aguilar, Pham Truong Thi Tho and L.P.A. Oyen, Ocimum basilicum, Plant Resources of South-East Asia (PROSEA). uses.plantnet-project.org · Reference work ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰
Andrea Nguyen, “Pho Garnish Plate”, from The Pho Cookbook, via The Splendid Table, 2017. splendidtable.org · Publication ↩ ↩²
Opinion of the Scientific Committee on Food on Estragole, European Commission, 2001. food.ec.europa.eu · Regulator ↩ ↩² ↩³ ↩⁴
“Alkenylbenzenes in food: how large is the health risk?”, BfR Communication No. 22/2022. bfr.bund.de · Regulator ↩ ↩² ↩³
Andy Ricker with J.J. Goode, “Stir-fried chicken with hot basil”, from Pok Pok, via The Splendid Table. splendidtable.org · Publication ↩ ↩²
“Flavorful Herbs”, LSU AgCenter. lsuagcenter.com · Reference work ↩
Nagi Maehashi, “Thai Basil Chicken”, RecipeTin Eats, 2019 (updated 2025). recipetineats.com · Publication ↩
Pailin Chongchitnant, pad kra pao beef recipe, Hot Thai Kitchen. hot-thai-kitchen.com · Publication ↩

Basil vs. Thai Basil: Same Species, Different Herb in the Pan