Last weekend, we had a nice hike up Price Peak in the Sierras.
We went from sea level to above 10,000 feet (3,000 m) in about 6 hours. And I had a ROARING headache. I could hear my heart beat in my ears at all times. My entire head throbbed.
But, honestly, I was expecting it. We changed altitude too fast. But I felt fine otherwise (I wasn't nauseous).
Should I be worried when I get a headache due to altitude change? What are the signs I should be watching out for, if not headaches?
Headaches are common symptoms of altitude sickness. It's a sign your brain is not getting enough oxygen.
As with lots of mountain issues it's down to judgement. If the headache is impairing your ability to perform at altitude, then yes, it's dangerous. If you can't concentrate on what your doing then your a danger to yourself and others.
Bear in mind, you're not necessarily the best person to make the decision on whether to go on or go down. If you're alone, bear on the side of caution: head down. If you're in a group, tell the other people how you feel so they can keep an eye on you.
A headache on its own is unlikely to kill you. You're unlikely to simply have an aneurysm and keel over.
Other symptoms of altitude sickness listed on the NHS web site are:
If you get the below issues, get down ASAP, call mountain rescue, whatever— just get down now!
These are symptoms of high altitude pulmonary oedema (HAPE). This means you effectively drown in your own fluids. Not good...
Obviously, the main way to avoid these issues is to acclimatise properly.
You are right, if you gain 3000+ meters within 6 hours, you are susceptible to AMS. A safe vertical height gain per day would be around 1000 meters. But since your question is more about what other symptoms to watch out for to identify AMS, here are a few that you can keep an eye on:
Your concern about headache is a valid one. But also keep in mind that headache is very normal at higher altitudes. Almost everyone does go through this during the initial times of acclimatization. Usually the headache goes off as one gets used to the thin air. HAPE and HACE are life threatening conditions. Usually HAPE is the only one known to affect people at relatively lower altitudes (3000m). HACE is known to affect people around 4500+ meters. The symptoms of HAPE have already been given by Liam.
Things to remember:
PS: I did get a doubt that you might have been a victim of dehydration. Another possibility might be a strong sun. (both can lead to headache the way you described)
If it's a nice summer's day at lowest avalanche warning level in mid altitude you can still be hit by an avalanche and die. That being said in reference to the answer of @BenCrowell and the comments, it's just a matter of chances which are relatively low to get AMS (which are effecting your body in a serious matter) in regions up to 3000 m or even slightly above.
With higher altitude the partial pressure of oxygen in the air decreases. While in a long-distance flight in about 10 km height the conditions are similar to air in 2000-2500 m altitude. With the decreasing partial pressure of oxygen in breathing air the partial pressure of the dissolved oxygen in your blood decreases. The oxygen saturation drops to about 90% for this height. Related to your condition which is affected by your predisposition or actual stress factors (which often occur on alpine tours) this decreased oxygen level will be balanced by an increased breathing rate and you will be also taking deeper breaths. For some people this isn't enough and they already notice the effect of the decreased oxygen saturation on their body very intensively.
It is proven that mountain tribes like the Sherpas have bigger red blood cells (hemoglobin) in consequence to their habitat. This is very admirable in my opinion and it shows the diversity of human being and the beauty of evolution. And like you know it's a major difference if you go from 1000 to 3000 m or if you start by sea level. The key is acclimatization.
I just recently have read about altitude sickness in Hochtour which is a quite new German book about alpine tours. I will share some general information I was getting from the chapter relating to AMS (acute mountain sickness):
How to avoid AMS?
Don't panic if you are getting headaches in higher altitudes. They are not unusual above e.g. 4000 m. If they are occurring together with other symptoms you should start to worry a bit more. Be cautious, listen to your body and ask your mates because sometimes you aren't able to judge by yourself anymore.
As your body gets used to the altitude, the symptoms go away. Therefore, if symptoms persist, Yes you should be worried.
Altitude sickness can affect your lungs and brain. When this happens, symptoms include being confused, not being able to walk straight (ataxia), feeling faint, and having blue or gray lips or fingernails. When you breathe, you may hear a sound like a paper bag being crumpled. These symptoms mean the condition is severe. It may be deadly.
10,000 feet is not very high. Most likely the headache you were experiencing was due to some combination of sleep deprivation, caffeine withdrawal, and unaccustomed exertion and aerobic challenge. It would be unusual to experience any discomfort whatsoever at that altitude. Most people don't need any acclimatization for that altitude. I've hiked with a lot of people on day hikes up to 10,000-11,000' in the Transverse Ranges of Southern California, and very few had even a headache. For comparison, La Paz, Bolivia, is at 12,000', and people don't keel over and die when they fly into La Paz from sea level.
At altitudes more like 12,000 to 14,000', it's more common for people to start to have discomfort (nothing life-threatening) due to pH imbalance in their blood. If you're going to these altitudes without acclimatization, or even higher altitudes with acclimatization, you may want to consider getting a prescription for diamox (acetazolamide), which helps to rebalance your blood pH.
Should I be worried when I get a headache due to altitude change?
No, not at 10,000', if "worried" means worried about dying. Of course, if you feel lousy, you feel lousy. You're not having fun. That could be a good reason to reconsider your options, such as turning around or waiting somewhere while your companions summit and then pick you up on the way back.
What are the signs I should be watching out for, if not headaches?
Wikipedia lists the following symptoms of high-altitude pulmonary edema (HAPE): "Symptoms: at least two of: Difficulty in breathing (dyspnea) at rest Cough Weakness or decreased exercise performance Chest tightness or congestion Signs: at least two of: Crackles or wheezing (while breathing) in at least one lung field Central cyanosis (blue skin color) Tachypnea (rapid shallow breathing) Tachycardia (rapid heart rate)."
