Before we started our Mount Toubkal hike, we were quite nervous about how we might be affected by altitude, and it is only when we were on the mountain did we discover how we were affected and then find coping strategies suitable for us.
I'm not going to claim this article offers definitive medical advice; it contains just my observations. However, if you take one message it is that altitude sickness is no joking matter and you shouldn't try to mask the effects it is having on you; this enables your guide can make a reasonable assessment about whether you should come off the mountain for your own safety.
Unfortunately hikers can't predict whether they might be affected, and the fittest of people can come down with symptoms before that fat old git you think is a "dead cert" succumbs. Obviously if you struggle to breathe at sea level (for example if you have some kind of lung disease) then it ain't gonna be pretty at 12,000 feet but that's about as far as you can estimate.
As it turns out, our experiences were fairly mild (and indeed the height we reached – around 12500 ft is at the lower end of "serious" in any case).
During our climb towards our first 11,000 footer, I found that I started getting something of a headache and felt a little dizzy. To help counter the effects, I reduced my stride length and slowed down my walking pace. Getting out of breath only makes things worse. I was unashamed in slowing up the walking group but staying safe is the name of the game. After 30-50 paces I also took just a couple of seconds to have a breather to stay on top of my heart rate. My beloved did it better; she just slowed right down but didn't have to stop walking at all, but kept on plodding her way to the summit.
Our walking companion Prakash on the other hand, felt panic about the impact he was feeling and just wanted to get to the top as quickly as he could so he could have a complete rest. As we were near the top when he started feeling it I guess he didn't put himself at great risk, but panic on a mountain top is never a wise idea. Our guide was certainly urging him to slow down.
It also helps to acclimatise over a few days. I was shocked that some people think it OK to climb Toubkal on a weekend and then jet off home. Our tour operator arranged it for us to climb higher and camp overnight at a lower altitude each evening for three nights before attempting the highest peak. That way you build up your red blood cells to make that final push that bit easier and most importantly safer.
Each evening our guide also set us a little puzzle to talk through, which I presume in part enabled him to check out whether our reasoning and logic had become so shot that we were unsafe to continue. Likewise, I did little sum calculations in my head and also wrote notes for my travel reviews. Reading back, my handwriting is rather scrappy but it makes sense.
We did notice we couldn't remember certain words during conversations, but again nothing so terrible as to make anyone think the other person shouldn't be up there. Obviously, one of the tricky things about altitude sickness is that you may not realise you are affected, and as such I would always personally recommend that if you are used to lower altitudes that you only take a hike over 10,000 feet with a guide in tow.
For anyone who feels my words about altitude sickness are over dramatic, one of the women in the other party going up Toubkal suddenly felt very poorly about 30 minutes after setting off for the summit, at perhaps 11,000 feet. Her guide shone his torch on her face and found that her lips and eyes were bulging and she also felt very weak and shivery. He took her down to the mountain lodge immediately, and arranged for her to have 2 hours of observation while he returned back to lead his group. While fortunately she didn't suffer any further after effects, next year she is arranging a beach holiday break.