The most common initial symptom of cavernous sinus thrombosis is a headache.
This usually develops as a sharp pain located behind or around the eyes that steadily gets worse over time.
It can be several days, or even weeks, before additional symptoms develop after the headache starts.
In most cases of cavernous sinus thrombosis, the eyes are affected. You may experience:
- swelling and bulging of the eyes – this usually starts in one eye and spreads to the other eye soon after
- red eyes
- eye pain – which can be severe
- vision problems – such as double vision or blurred vision
- difficulty moving the eyes
- drooping of the eyelids
Other symptoms of cavernous sinus thrombosis include:
- a high temperature of 38C (100.4F) or above
- seizures (fits)
- changes in mental state, such as feeling very confused
These symptoms usually occur if cavernous sinus thrombosis is left untreated, or if an infection causing the condition spreads throughout the body.
Without treatment, most people with cavernous sinus thrombosis will become increasingly drowsy and eventually fall into a coma.
When to seek medical advice
You should always contact your GP if you have a persistent and severe headache that you've never had before.
While it's highly unlikely to be caused by a cavernous sinus thrombosis, a persistent headache usually requires further investigation.
You should also contact your GP if you develop any of the eye symptoms described above.