| Cover | Nov. 18, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 18, 2021 |
| Entity File Number | 001-10526 |
| Entity Registrant Name | United-Guardian, Inc. |
| Entity Central Index Key | 0000101295 |
| Entity Tax Identification Number | 11-1719724 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 230 Marcus Boulevard |
| Entity Address, City or Town | Hauppauge |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 11788 |
| City Area Code | 631 |
| Local Phone Number | 273-0900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.10 par value per share |
| Trading Symbol | UG |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
