v3.26.1
Cover - shares
 6 Months Ended
Jun. 30, 2026
Aug. 03, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Current Fiscal Year End Date --12-31  
Document Transition Report false  
Entity File Number 001-43008  
Entity Registrant Name Atrium Therapeutics, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 39-4639499  
Entity Address, Address Line One 10578 Science Center Drive  
Entity Address, Address Line Two Suite 125  
Entity Address, City or Town San Diego  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92121  
City Area Code 619  
Local Phone Number 876-0700  
Title of 12(b) Security Common Stock, par value $0.001 per share  
Trading Symbol RNA  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   17,105,643
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Entity Central Index Key 0002093101  
Amendment Flag false