| Cover | Mar. 31, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 31, 2021 |
| Entity File Number | 001-36201 |
| Entity Registrant Name | IMMUNIC, INC. |
| Entity Central Index Key | 0001280776 |
| Entity Tax Identification Number | 56-2358443 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 1200 Avenue of the Americas |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Country | US |
| Entity Address, Postal Zip Code | 10036 |
| City Area Code | (332) |
| Local Phone Number | 255-9818 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 |
| Trading Symbol | IMUX |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
