Financial instruments - Foreign exchange risk (Details) - Foreign exchange risk € in Thousands	12 Months Ended
Dec. 31, 2025 EUR (€) € / £ € / ¥ € / $ item D
Financial risk management and financial instruments
Number of exchange rates used for CFaR approach \| item	50
Number of trading days in interval for CFaR approach \| D	21
Confidence level (as a percent)	95.00%
Holding period	1 year
Net exposure	€ 704,670
CFaR	€ 52,106
Cash flow hedges \| USD
Financial risk management and financial instruments
Average hedging rate \| € / $	1.1774
Cash flow hedges \| CNY
Financial risk management and financial instruments
Average hedging rate \| € / ¥	8.2921
Cash flow hedges \| GBP
Financial risk management and financial instruments
Average hedging rate \| € / £	0.8754
Cash flow hedges \| Less than 1 year \| USD
Financial risk management and financial instruments
Notional amount	€ 245,536
Cash flow hedges \| Less than 1 year \| CNY
Financial risk management and financial instruments
Notional amount	163,366
Cash flow hedges \| Less than 1 year \| GBP
Financial risk management and financial instruments
Notional amount	38,388
Cash flow hedges \| 1 - 3 years \| USD
Financial risk management and financial instruments
Notional amount	44,743
Cash flow hedges \| 1 - 3 years \| CNY
Financial risk management and financial instruments
Notional amount	28,367
Cash flow hedges \| 1 - 3 years \| GBP
Financial risk management and financial instruments
Notional amount	€ 4,835

The percentage of confidence level used as an assumption.

No definition available.

Name:	fms_ConfidenceLevelPercentage
Namespace Prefix:	fms_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum holding period of financial instruments, used as an assumption, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	fms_MaximumHoldingPeriod
Namespace Prefix:	fms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of exchange rates used for CFaR approach

+ References

No definition available.

+ Details

Name:	fms_NumberOfExchangeRatesUsedForCfarApproach
Namespace Prefix:	fms_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of trading days in interval for CFaR approach

+ References

No definition available.

+ Details

Name:	fms_NumberOfTradingDaysInIntervalForCfarApproach
Namespace Prefix:	fms_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The average price of a hedging instrument. [Refer: Hedging instruments [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 23B
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_23B_b&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_AveragePriceOfHedgingInstrument
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfRiskManagementStrategyRelatedToHedgeAccountingLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_112_c&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_NotionalAmount
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of risk exposure associated with financial instruments with a shared characteristic that identifies a concentration of risks. [Refer: Classes of financial instruments [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph B8
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_B8_c&doctype=Appendix&subtype=B
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_RiskExposureAssociatedWithInstrumentsSharingCharacteristic
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The measure of a potential loss exposure as a result of future market movements, based on a specified confidence interval and measurement horizon.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2025-01-01
-Paragraph 41
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2025-en-r&anchor=para_41&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_ValueAtRisk
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_TypesOfRisksAxis=ifrs-full_CurrencyRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfHedgesAxis=ifrs-full_CashFlowHedgesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_USD
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_CNY
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=currency_GBP
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_NotLaterThanOneYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanOneYearAndNotLaterThanThreeYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: