Is acute mountain sickness repeatable?

Question

Several month ago me and my climbing partner were climbing a mountain over 7000m. In first few day my climbing partner got AMS. It was high-altitude pulmonary edema (he felt very bad, he had strong cough with blood). So we gave him an injection of Dexamethasone and safely returned him home.

He was treated for about a month and now he's healthy. He is doing different sports like cycling, running etc...

We are going to climb another mountain ~5000m. I'm afraid of repeating described situation. I have tried to read about medical research on this topic but unable to find the answer.

Answer 1

Yes, he can get it again and in fact people with a history of altitude sickness have a higher risk of getting it again.

Risk factors for altitude illness include rapid ascent, strenuous physical exertion, young age, living at a low altitude, and a history of altitude illness.

Altitude Illness: Risk Factors, Prevention, Presentation, and Treatment

If you have a previous history of suffering from acute mountain sickness, then you are probably more likely to get it again.

Altitude Sickness

There was also a study done on this question

"Return to Activity at Altitude After High-Altitude Illness"

Sports and other activities at high altitude are popular, yet they pose the unique risk for high-altitude illness (HAI). Once those who have suffered from a HAI recover, they commonly desire or need to perform the same activity at altitude in the immediate or distant future.

...

In addition to the type of HAI experienced and the current level of recovery, factors needing consideration in the return-to-play plan include physical activity requirements, flexibility of the activity schedule, and available medical equipment and facilities. Most important, adherence to prudent acclimatization protocols and gradual ascent recommendations (when above 3000 m, no more than 600-m net elevation gain per day, and 1 rest day every 1 to 2 ascent days) is powerful in its preventive value and thus strongly recommended.

...

Conclusion:

With a thoughtful plan, most recurrent HAI in athletes can be prevented.

Return to Activity at Altitude After High-Altitude Illness

So it looks like while your friend does have a higher risk, it doesn't mean that he has to stop, just that you need to be more careful and ascend slower next time. Given that you already made this awful experience and are researching the topic, you probably already know this: You need to read up on and consult a professional about how to acclimatize correctly and most importantly, how to detect signs of AMS. You must be able to turn around and seek lower terrain before it gets as bad as developing pulmonary edema.