Instagram and Facebook both appear to be suffering major outages, with thousands of app users claiming they are unable to refresh their feeds or upload photos or videos.
Instagram, which is owned by Facebook, has been experiencing issues since around 2pm GMT, according to Downdetector, which monitors online outages.
Downdetector's outage map shows that users in the UK, East Coast of the United States and Brazil are the worst affected.
The majority of users are reporting problems with their news feeds, while others are also experiencing problems logging into the app and accessing the Stories feature.
'Instagram not working, can't refresh feed, followers list not loading, tagged photos not loading, etc. Tried restarting phone, deleting and re-downloaded app, still not working. Anyone else?!' one desperate user wrote on the Downdetector forum.
The Facebook and Facebook Messenger apps started experiencing issues at around the same time, according to Downdetector - although the problems seem to be less widespread.
Facebook users are complaining they are unable to login, and that they can't upload pictures, with a few reporting a 'total blackout'.
'Couldn’t go live, post pictures or anything kept saying check network.. tried log out and back in and can’t log in keeps saying error,' one user wrote on the Downdetector forum.