The major commuter route was closed for over two hours and a man was hospitalised following the crash at 6.45am.
The collision occurred in the Dublin-bound lanes shortly before Junction 12 at Newtownmountkennedy.
A man in his 40s was cut from a car and taken to Vincent’s Hospital with non life-threatening injuries.
Transport Infrastructure Ireland had earlier warned of low road temperatures on the N11 and along the east Leinster region in general. AA Roadwatch had cautioned motorists about cold weather conditions cross the country, with patches of frost in many places. A spokesperson added: "If you're on frosty roads, slow down and leave extra space."Subscribe or register today to discover more from DonegalLive.ie
Buy the e-paper of the Donegal Democrat, Donegal People's Press, Donegal Post and Inish Times here for instant access to Donegal's premier news titles.
Keep up with the latest news from Donegal with our daily newsletter featuring the most important stories of the day delivered to your inbox every evening at 5pm.