| Cover | May 09, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | May 9, 2022 |
| Entity File Number | 001-38410 |
| Entity Registrant Name | BioXcel Therapeutics, Inc. |
| Entity Central Index Key | 0001720893 |
| Entity Tax Identification Number | 82-1386754 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 555 Long Wharf Drive |
| Entity Address, City or Town | New Haven |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06511 |
| City Area Code | 475 |
| Local Phone Number | 238-6837 |
| 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 $0.001 |
| Trading Symbol | BTAI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | true |
