Due to the high altitude, hikers will typically experience shortness of breath and mild altitude sickness even at a relatively slow walking pace, when they climb Kilimanjaro.
Other common symptoms of altitude sickness while climbing Kilimanjaro include headaches, nausea and dizziness. Loss of appetite and insomnia are also common. More severe symptoms include blurred vision, disorientation and the inability to continue walking.
If such symptoms arise, immediate descent assisted by your guide is imperative to avoid more serious and lasting consequences.