Symphytum officinale

Other names: Kostival

Large leaves; alkaloids—internal use needs caution.

Thick root and pointed leaves.

Family: Boraginaceae
Plant type: Perennial herb
Safety level (indicative): High risk for internal use

What the safety levels mean (expand legend)

Generally recognised as safe. Often a common herb with reasonable harvest and use; still read the specific warnings on the card.
Information. Primarily informational — details in the text and warnings below matter most.
Caution. Needs extra care (dose, duration, sensitive groups, interactions).
Risky. Significant risks — verify sources, contraindications and professional guidance.
Not for home experimentation. Not suitable to experiment with at home without knowledge and certainty.
High risk for internal use. Particular risk with internal use (e.g. alkaloids); avoid prolonged or irresponsible dosing.
Not specified. Level not filled in yet — rely on individual warnings and links below.

Kostival lékařský — habitus rostliny (Wikimedia Commons). — Fotografie na Wikimedia Commons (CC BY 2.5).
Plant habit

Safety — read before use

For this herb it is important to check warnings, mix-ups and cautions. Start with the Safety section.

Quick overview

A practical summary; details are in the sections below.

Safety grade: High risk for internal use·details
Scientific sources on the card: Yes — sources are listed with claims·Science section
When and what to harvest: Leaf — April–May
Full harvest section
Processing methods: Decoction, Herbal oil, Poultice / compress
All methods and recipes on the card
Topics and symptoms: Joints & mobility, Muscles after exertion, Skin
Topics section · Symptoms overview

Identification and mix-ups

Purple flowers in branching cymes.

Possible mix-ups and risks

Pyrrolizidine alkaloids—risk with long-term internal use.

Similar herbs

Equisetum arvense
Obě vyžadují obezřetnost u dlouhodobého vnitřního užití / čistoty sběru — sleduj karty a zdroje.

Topics and symptoms

More topics are in the symptoms and topics overview.

Joints & mobility
Traditional· Traditional / cultural framing
Muscles after exertion
Traditional· Traditional / cultural framing
Skin
Traditional· Traditional / cultural framing

Geographic occurrence

Czechia
Common (expected wild occurrence in the region)
Austria
Common (expected wild occurrence in the region)
Germany
Common (expected wild occurrence in the region)
Hungary
Common (expected wild occurrence in the region)
Poland
Common (expected wild occurrence in the region)
Slovakia
Common (expected wild occurrence in the region)

Harvest

LeafApril–May
jaro
Region: Czechia
Notes: Harvest note (full translation pending): Listy pred kvetem.

Storage

Drying(Leaf)
Sušený rostlinný materiál uchovávej v uzavřené nádobě.
Light:
Mimo přímé UV.
Moisture:
Nízká relativní vlhkost.

Processing methods on this herb card

Decoction(Leaf)Suitability: Medium suitability
Longer simmering of plant material in water.
Full method description (from the catalogue)
A decoction is made by simmering plant material in water — often around 10–20 minutes depending on tradition and plant part. Denser parts (roots, bark, some seeds) are often prepared more reliably this way than with a short infusion.
Compared with an infusion it can extract more compounds, but also more tannins or bitterness; the flavour profile differs from a delicate tea. Combine this overview with the herb card for suitable plant part and contraindications.
Traditional context for this method: yes·Scientific context for this method: no
Procedure (recipe)
Comfrey leaf decoction for external compressing
About 20 min · Difficulty: Advanced
1. For about 500 ml water use 2 tsp dried leaf (from a verified source only).
2. Simmer 10–15 minutes under a lid, strain, and cool to a comfortable temperature.
3. Soak a clean cloth in the liquid and apply to intact skin for 10–20 minutes; do not drink the preparation.
Comfrey contains pyrrolizidine alkaloids — internal use is not appropriate; follow warnings on the herb card and EMA monographs. External and short-term only.
Why this way (extraction / behaviour of constituents)
European texts often focus on comfrey root for assessed traditional external use; leaf material is less standardised. Pyrrolizidine alkaloids are the main safety concern with ingestion and prolonged heavy exposure. A short, dilute application to intact skin as a compress is not the same pharmacokinetic route as drinking the decoction — still follow warnings on the herb card and do not drink these preparations.
What is typically released
orientační domácí extrakce — profil závisí na teplotě, času řezu a poměrech
Solvent / water
mediální složení (voda, alkohol, olej, med…) viz jednotlivé kroky
After preparation
po přípravě uchovávej hygienicky a podle typu výrobku (chlad, světlo, alkohol)
Extra literature for the recipe
- Vyhledávání studií (PubMed apod.)Konkrétní vědecká tvrzení ověř na kartě byliny a v primární literatuře.
Herbal oil(Leaf)Suitability: Medium suitability
Macerating herbs in a vegetable oil (cold or with gentle heat).
Full method description (from the catalogue)
Herbal oil is made by steeping dried or fresh material in oil (e.g. olive, sunflower) over time, sometimes with gentle warming. The result is not steam-distilled essential oil — it is a different extract type and usage (often topical or culinary per recipe).
Temperature, light, and material moisture affect shelf life; rancid oil must be discarded.
Traditional context for this method: yes·Scientific context for this method: no
Procedure (recipe)
Comfrey leaf oil (external only)
About 40 min · Difficulty: Advanced
1. Chop dried leaf and fill a jar about one third full, then cover with olive or sunflower oil.
2. Macerate 4–6 weeks in a warm shady place, then strain through cloth.
3. Use on intact skin only after a patch test on the inner forearm — do not consume; pyrrolizidine alkaloids are risky with internal exposure.
EMA-style texts discuss comfrey root for traditional short-term external adult use; treat leaf cautiously and only externally — see the herb card.
Why this way (extraction / behaviour of constituents)
Regulatory texts often address comfrey root for traditional short-term external adult use; leaf material is less standardised and pyrrolizidine alkaloids are a documented concern for internal exposure. A home macerated oil is a variable extract for unbroken skin only — not equivalent to assessed herbal medicines.
What is typically released
orientační domácí extrakce — profil závisí na teplotě, času řezu a poměrech
Solvent / water
mediální složení (voda, alkohol, olej, med…) viz jednotlivé kroky
After preparation
po přípravě uchovávej hygienicky a podle typu výrobku (chlad, světlo, alkohol)
Extra literature for the recipe
- Vyhledávání studií (PubMed apod.)Konkrétní vědecká tvrzení ověř na kartě byliny a v primární literatuře.
Poultice / compress(Leaf)Suitability: Low suitability
Liquid or paste on the skin, often through a thin cloth.
Full method description (from the catalogue)
A compress applies moist warm or cool material to the skin directly or through fabric. Duration and temperature are key — too hot can burn; too long can macerate the skin.
Use clean textiles and watch skin reaction during the first minutes.
Traditional context for this method: yes·Scientific context for this method: no
Procedure (recipe)
Compress with cooled comfrey leaf infusion
About 25 min · Difficulty: Advanced
Extraction parameters (rough guide): 250 ml water · 100 °C · 5–10 min boil
1. Make a weak decoction from dried leaf (see herb card — external use only), strain, and cool.
2. Soak a clean cloth and apply to intact skin for 10–15 minutes.
3. Do not drink the liquid — pyrrolizidine alkaloids; follow warnings on the herb card and EMA texts.
External and short-term only; leaf is not approved for routine internal use in common European frameworks.
Why this way (extraction / behaviour of constituents)
European texts often focus on comfrey root for assessed traditional external use; leaf material is less standardised. Pyrrolizidine alkaloids are the main safety concern with ingestion and prolonged heavy exposure. A short, dilute application to intact skin as a compress is not the same pharmacokinetic route as drinking the decoction — still follow warnings on the herb card and do not drink these preparations.
What is typically released
Polární frakce v horké vodě pro zevní obklad; neinterpretuj jako koncentraci pro vnitřní užití.
Solvent / water
Voda; po vychladnutí aplikuj výluh zevně.
After preparation
Použij co nejdříve po přípravě; skladuj krátce v chladu jen při čisté práci.
Extra literature for the recipe
- EMA HMPC — Symphytum officinale, radixText se vztahuje primárně ke kořeni v přípravcích; toxikologický kontext PA je paralelní k opatrnosti u celé rostliny.
- EFSA — pyrrolizidinové alkaloidy v potravě a krmivechObecný rámec rizik PA; nepřenášej mechanicky na domácí dávky.

Traditional / spiritual use

Kept separate from science — entries are cultural or symbolic, not medical advice.

Related guides in the library

Comfrey in folk memory: poultices outside, caution inside
General
Traditional useFolk useHerbal lore
Comfrey carries historic names hinting at bone and external poultices. Modern evidence warns strongly about internal use; the spiritual line here stays with careful body care and the card warnings, not with promises of cure.
Form:
obklady v minulosti, odvar v tradici
Claim strength:
Tradition
Source note:
Historical names and external-use lore — contrast with internal-use risks on the card.

Scientific notes

Each claim lists a study type and a source (URL or DOI) where available. Dose notes from the literature are informational only.

How to read evidence strength and study type labels

Labels summarise how the catalogue entry is tagged — they are not a medical verdict on efficacy. For every row, read the summary, limitations and source link.

Evidence strength

Evidence level not specified: The author did not grade the record; judge from the summary, limitations and source link.
Narrative / orientational literature: Descriptive or expert literature without controlled group comparison — context rather than proof of effect.
Weak evidence: Study or conclusion with major methodological limits; treat only as a pointer for further reading.
Preliminary findings: First or smaller studies — interesting direction, not the final word on efficacy or safety.
Moderate strength of evidence: Moderate strength by study design; sample and context limits still apply.
Stronger evidence: Stronger design or consistency of results within the study’s stated limits.
Review article: A review summarises multiple sources; quality depends on review method and field.

Study type

Narrative / expert text: Expert text or overview without a classical study design.
In vitro study: Cell culture or test-tube experiment — does not show an effect in the body.
Animal study: Animal model — transfer to humans is not automatic.
Observational study: Observing groups without random treatment assignment; confounding is possible.
Clinical trial: Human clinical trial; sample size and control group matter.
Randomised controlled trial: Randomised controlled trials are among the stronger designs when well conducted.
Review study: A review aggregates multiple papers — quality depends on selection rules.
Systematic review: Systematic review with explicit search and selection methodology.
Meta-analysis: Statistical pooling of studies; outcome depends on input data and heterogeneity.
Regulatory assessment / monograph (EMA, WHO…): Regulatory body summary for a herbal product — different context from a single RCT; often about products, not home tea.
Expert monograph (herbal preparations): Structured literature summary for a plant or drug — quality depends on author and edition year.

Comfrey root and leaf contain pyrrolizidine alkaloids; regulators therefore discourage internal use. External traditional use is debated and still carries residue and species issues.
Stronger evidenceNarrative / expert textYear: 2016
Active compound / focus: pyrrolizidinové alkaloidy (obecně)
Limitations: Hepatotoxicity risk with chronic internal exposure; topical safety is not trivially guaranteed; follow national monographs and clinician advice.
EMA Committee on Herbal Medicinal Products (HMPC) — European Medicines Agency
EMA: Final assessment report on Symphytum officinale L., radix
Evidence summary (full translation pending): EFSA hodnoti 1,2-nenasycene PA jako genotoxicke karcinogeny a sleduje expozici z potravin, medu a bylinnych nalevu; duraz na ochranu citlivych skupin a na limity v potravnim retezci.
Stronger evidenceReview studyYear: 2011
Active compound / focus: pyrrolizidinové alkaloidy (1,2-nenasycené)
Limitations: Limitations (translation pending): Opinion se netyka jednotliveho produktu z kostivalu; jde o obecny ramec expozice PA z rostlinnych zdroju; pro konkretni pripravek hledejte narodni limity a monografie.
EFSA Panel on Contaminants in the Food Chain (CONTAM) — EFSA Journal
Scientific Opinion on pyrrolizidine alkaloids in food and feed (EFSA)
DOI: 10.2903/j.efsa.2011.2406

Images

The main photo is in the card header. More images will appear here when available.

Safety

What the warning types mean

The type on each warning helps group themes — it does not replace the separate severity badge.

Internal use: Risks from swallowing, extracts, duration of use or concentration for internal use.
Interactions / medicines: Possible effect on medicines or concurrent treatment — check sources and a professional.
Raw plant parts: Raw, unripe or poorly prepared plant parts can be dangerous.
Toxins and regulation: Toxic constituents or regulated compounds (e.g. in distillates).
Contact with the plant: Skin or mucosa irritation from contact with fresh plant or sap.
Allergy: Allergic reactions, often linked to family sensitisation.
Harvesting and contamination: Contamination, species mix-ups or harvesting from unsuitable places.

Safety information (full translation pending)High severityInternal use
This warning is being translated to English. Czech editor text: Pyrrolizidinove alkaloidy Dlouhodobe vnitrni uziti muze byt rizikove — konzultuj odborne zdroje.