Symptoms of Subarachnoid Hemorrhage (SAH): Hyper-Dangerous Signs—From the "Worst Headache" at 1 Minute to Signs of Re-bleeding and Vasospasm

Subarachnoid Hemorrhage (SAH) is an extremely dangerous condition where the subsequent prognosis is often determined within just the first few minutes after onset. The symptoms are dramatic, with the “worst headache ever experienced” appearing in nearly 100% of patients.

Symptoms of Subarachnoid Hemorrhage (SAH): Easy to Understand Timeline

Timing	Symptoms (Almost 100% Present)	Common Symptoms (50–80% Present)	Rare but Ultra-Dangerous Signs (Immediate Death Risk)
Onset ∼1 Minute	Worst headache ever experienced, like being struck in the back of the head with a hammer.	Brief loss of consciousness (seconds ∼ minutes); Vomiting (projectile).	Sudden collapse and respiratory arrest.
1 ∼ 30 Minutes	Headache peaks (level 10 out of 10).	Neck becomes stiff (cannot bend neck); Photophobia (light sensitivity).	Seizure attack.
1 ∼ 6 Hours	Headache slightly subsides but is still severe.	Dazed, sluggish reaction to calls; Slight difficulty moving limbs.	Re-loss of consciousness →Re-bleeding.
6 ∼ 24 Hours	Headache may intensify again in some.	Nuchal rigidity (Neck is stiff as a board).	Sudden fall into sleep-like unconsciousness.
3 ∼ 14 Days	Headache gets better but suddenly returns severely (Vasospasm).	Hemiparesis, difficulty speaking, increased drowsiness.	Sudden impaired consciousness → Cerebral infarction (stroke).
2 Weeks ∼ 1 Month	Headache is mostly gone.	Dazed, memory loss, unsteadiness due to hydrocephalus.	Sudden falling asleep and not waking up → Hydrocephalus.

5 Major Symptoms Families Must Remember: “If You See This, Call 911 Immediately!”

Rank	Symptom	Incidence	Absolutely DO NOT “Wait and See” If Reported!
1	“Worst headache ever” / “Hit by a bat”	95%	The No. 1 sign; this alone makes SAH 99% likely.
2	Sudden vomiting (especially projectile)	70%	Headache + Vomiting is almost certain confirmation.
3	Loss of consciousness, even briefly	50%	Dangerous, even if the patient recovers quickly.
4	Neck is stiff and cannot bend forward	80%	Tends to appear around 6 hours after onset.
5	Light hurts the eyes/cannot open eyes (Photophobia)	60%	Headache that is rarely relieved by painkillers.

Diseases that Mimic SAH (Differential Diagnosis)

Disease	Headache Severity	Loss of Consciousness	Neck Stiffness	Bleeding Visible on CT?
SAH	★★★★★	Common	Common	Visible in 99%
Migraine	★★★☆☆	No	No	Not Visible
Cluster Headache	★★★★★	No	No	Not Visible
Thunderclap Headache (New-onset Migraine)	★★★★★	Rare	No	Not Visible
Intracerebral Hemorrhage(Putamen/Thalamus)	★★★★☆	Rare	Rare	Visible, but in a different location

→ Therefore, if the “Worst Headache” occurs, the golden rule is to get a Head CT scan immediately (it provides a diagnosis in 5 minutes).