1. You have an exertional headache

Have an exertional headache means your pain is triggered by some physical activity. It is described as a pulsating pain on both sides of the head and can last from few minutes to several days. This pain is only triggered by exercise and is usually developed when you work out at high altitudes or in warm weather. Exertional headaches can be primary or secondary. Primary exertional headaches have unknown reasons but are thought to be caused by narrowing of blood vessels that happen during an exercise. Secondary exertional headaches are usually caused by an underlying condition that can be simple, or not. Usually, this headache is followed by other symptoms such as neck stiffness, vomiting, congestion, vision issues, or others.

If you get this headache very frequently, it is recommended that you book an appointment with your doctor to rule out the possibility of having serious issues. As for primary headaches, these will fade away alone after few months. You can take over-the-counter anti-inflammatory medications like ibuprofen, or apply heating pads to your head to allow blood vessels to open up.

2. You’re dehydrated

Being dehydrated means that your body is losing more fluids than it is consuming. This can be caused by excessive sweating during exercises. Not drinking enough water before exercising can lead to dehydration, and a headache counts as one of the primary signs of dehydration. Other symptoms could include; dry skin and mouth, heightened sense of thirst, constipation, decreased urine output, fatigue, feeling lightheaded or dizzy, or producing fewer tears. When your symptoms get worse, it means that you could have severe dehydration which is a medical emergency.

To treat mild dehydration you need to drink lots of fluids and electrolytes. Rather than choosing sports drinks that are rich in sugar and could worsen your headache, opt for unsweetened coconut water.

To prevent dehydration it is recommended that you drink 1 to 3 cups of water within 1 or 2 hours of working out. You can also keep a water bottle with you all the time during your workout to keep your body hydrated as you are sweating. Also, make sure you drink a cup of two after your training.

1. You’ve spent too much time in the sun

Being exposed to the sun can be a big trigger for headaches, whether you are working out or not.

To treat headaches caused by sun exposure, get out of the sun as soon as possible. Spend some time in a low-light or darkroom. Try to cool your body down by drinking water and using a damp washcloth on your eyes and forehead. You can also take a nonsteroidal anti-inflammatory like ibuprofen.

Source:

https://www.healthline.com/health/headache-after-exercise#sunlight