He should be taking a cough suppressant.
The coughing activates the vagal nerve. which slows the heartrate and causes the momentary blackout. It can happen to anyone at any age.
If in a restaurant, have him lie down, don;t get up, elevate his feet and let hiom rest for a few minutes.
If he starts to cough while driving IMMEDIATELY brake and pull over.
The cause of the coughing should be evaluated, of course, but in the meantime over-the-counter cough suppressants, especially when driving.
Could be bronchospasm. And all the coughing increases the intracranial fluid pressure in the head and can cause fainting. Does he have an inhaler? Not for asthma, but for the spasms. Not sure what all the stress test shows, sorry. Ask your doctor about this!
Hi
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This looks like a severe asthma like condition. X-ray and CT scan of chest and pulmonary function tests should be done. Please consult a chest specialist. It would be wise if he stays away from driving and heavy machinery until then.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!
Sometimes anti hypertensives can cause a cough. Get in touch with your GP. More common than you know. He may need a change in meds.