The first one is an emergency. The tenth is a pattern.

WHAT SETS IT OFF · EXERTION

A throbbing, two-sided headache during or after exercise or other long effort is usually primary exertional headache. That holds when it repeats the same way and has already been checked. It is benign, meaning harmless. A first sudden, severe headache that peaks within about a minute during exertion is an emergency. That is because it can be the first sign of a bleed.

A headache that comes during or right after effort has a short, specific list of possible causes. The first time it happens, it deserves more attention than it usually gets.

What does an exertional headache feel like?

Both sides, throbbing, coming on during or after long exertion. It lasts minutes to a couple of days. It is more common in heat and at altitude. It is more common in people who already have migraine. And it is benign. But the diagnosis is made only after the dangerous causes have been considered. The reason is that a first subarachnoid hemorrhage, bleeding around the brain, can look exactly like this.

Picture a pattern of repeated, identical exertional headaches that build slowly over months. They have already been checked. That is a different situation from one that happened for the first time yesterday.

What else causes a headache after exercise?

• Dehydration and heat — the most common contributor by far. It is also the easiest to test: fix it and see.
• Low blood sugar — training on an empty stomach, or a long gap since eating.
• Neck and shoulder load — cycling posture, overhead lifting, a fixed gaze.
• Breath-holding under load — the Valsalva part, which is bearing down with the airway shut. It overlaps with cough and strain headache.
• Caffeine timing — a pre-workout dose on an empty stomach.

How do I stop getting exercise headaches?

Once it has been checked, the real levers are load and fuel. Warm up slowly instead of starting hard. Drink before training, not during. Eat something first. Do not hold your breath through heavy lifts. Two biological drivers set how easily it fires: blood sugar stability and the body-wide inflammatory terrain. The third is the training schedule itself. People treat it as fixed, but it is the easiest part to adjust.

Frequently asked questions

Should I stop exercising?

No, once it has been assessed. Overall, exercise protects against frequent headaches. What usually needs adjusting is how fast you ramp up and how you fuel.

Is exertional headache dangerous?

Primary exertional headache is benign. The first sudden severe one is treated as an emergency, because it can be the first sign of a bleed.

Do I need imaging?

For a first or unusual exertional headache, usually yes. See when imaging is indicated.

Why only sometimes?

Because it is a threshold effect. The same workout sets it off on a hot day when you are under-fed and under-slept. On other days it does not.

How long does an exercise headache last?

Primary exertional headache lasts anywhere from a few minutes to a couple of days. It comes on during or after long effort. It throbs on both sides and repeats the same way each time. A headache that breaks that pattern needs to be assessed before it is called benign. So does the first one you have ever had.

What does a dangerous headache during exercise feel like?

It is sudden and severe. It reaches full strength within about a minute during the effort. A stiff neck, vomiting, confusion or any change in strength, speech or vision makes it more urgent. Treat that as an emergency today, without exception, because the first sign of a bleed can look exactly like a benign exertional headache.

Who is more likely to get headaches after working out?

People who already have migraine get them more often. They are also more common in heat and at altitude. Several things make them easier to set off. Training on an empty stomach. Running short on fluids. Holding your breath through heavy lifts. A pre-workout caffeine dose on an empty stomach. A first one after age 40 always gets assessed.

Compare

• Cough and strain
• Dehydration
• Emergencies
• Sleep
• Migraine