Acute mountain sickness (AMS) is caused by a lack of oxygen in the body of individuals exposed to higher elevations. This usually occurs when they travel to an altitude over 10,000 feet (3,000 metres) without proper acclimatization before engaging in physical activities. Mountain climbers, trekkers, skiers, and travelers to the Andes or Himalayas, etc.

While individual tolerance varies, symptoms usually appear within several hours of ascending, with those in poor physical condition being most susceptible. Headache, fatigue, shortness of breath, nausea, and poor appetite occur initially. Inability to sleep is also frequently reported. In more severe cases thinking and judgment may become impaired. 

The symptoms of acute mountain sickness can be prevented or minimized by gradually ascending (less than 500 meters/day) over several days to give your body a chance to acclimatize to the higher altitude.

Once the symptoms begin to occur, they usually subside over several days without treatment provided there has been adequate time for acclimatization. However, if they worsen, they can be relieved with the administration of oxygen or descent to a lower altitude.

Following are some useful medicine for AMS:

1. Diamox

This is the most tried and tested drug for altitude sickness prevention and treatment. Unlike dexamethasone, this drug does not mask the symptoms but actually treats the problem. It seems to works by increasing the amount of alkali (bicarbonate) excreted in the urine, making the blood more acidic. Acidifying the blood drives the ventilation, which is the cornerstone of acclimatisation.

For prevention, 125 to 250mg twice daily starting one or two days before and continuing for three days once the highest altitude is reached, is effective. Blood concentrations of acetazolamide peak between one to four hours after administration of the tablets. Studies have shown that prophylactic administration of acetazolamide at a dose of 250mg every eight to twelve hours before and during rapid ascent to altitude results in fewer and/or less severe symptoms (such as headache, nausea, shortness of breath, dizziness, drowsiness, and fatigue) of acute mountain sickness (AMS). Pulmonary function is greater both in subjects with mild AMS and asymptomatic subjects. The treated climbers also had less difficulty in sleeping.

Gradual ascent is always desirable to try to avoid acute mountain sickness but if rapid ascent is undertaken and actazolamide is used, it should be noted that such use does not obviate the need for a prompt descent if severe forms of high altitude sickness occur, i.e. pulmonary or cerebral oedema.

Side effects of acetazolamide include: an uncomfortable tingling of the fingers, toes and face carbonated drinks tasting flat; excessive urination; and rarely, blurring of vision. On most treks, gradual ascent is possible and prophylaxis tends to be discouraged. Certainly if trekkers do develop headache and nausea or the other symptoms of AMS, then treatment with acetazolamide is fine. The treatment dosage is 250 mg twice a day for about three days. A trial course is recommended before going to a remote location where a severe allergic reaction could prove difficult to treat if it occurred.

Diamox

2. Dexamethasone

This is a drug that decreases brain and other swelling reversing the effects of AMS. The dose is typically 4 mg twice a day for a few days starting with the ascent. This prevents most of the symptoms of altitude illness from developing.

WARNING:  Dexamethasone is a powerful drug and should be used with caution and only on the advice of a physician and should only be used to aid acclimatisation by sufficiently qualified persons or those with the necessary experience of its use.

Dexamethasone

3. Rhodiolae (红景天), purchase in China only

A traditional healthcare product of Tibetans that can strengthen your body and alleviate high altitude sickness; take it at least 10 days in advance. 

As a natural plant growing in the pure snow area at 3500-5000 meters high, it contains rich Rhodioloside and Aglycone tyrosol which is not only resistant to fatigue, hypoxia, microwave radiation, but also can regulate nervous system and metabolism, and most importantly, can help you adapt to the environment. Normally its root and rootstock are used into medicines, but the whole plant can also be used.     

In fact, Rhidiolae has been applied over 2000 years ago by people from Tibetan Plateau into medicines to build up their bodies and resist the effects of disagreeable environment. It is also normal to see people put it in drinking water and wine to relieve fatigue or shield themselves from cold as well as to prevent diseases and supplement nourishment. Due to its functions of maintaining health and enriching blood and nourishing lung, it has been regarded by Tibetan doctors as one of the ‘three treasures ’. When there is inadequate oxygen, we will show symptoms of hypoxia, including headache, tiredness, difficult breathing and dizziness, etc, or coma or even death if it’s severe or sudden. Generally speaking, it usually happens on the plateau area, which will lead to mountain sickness or deadly complications. Hypoxia, a tension stimulation, will result in a series of stress reaction. As an adaptogen, Rhidiolae can improve the body’s nonspecific resistance against destructive stimulus together with its adaptation ability. In the case of hypoxia, it effectively raises the body’s adaptation to lack of oxygen by accelerating the oxygen diffusion of our cells or improving the use efficiency of the oxygen and our body’s oxidation resistance     

Rhodiolae (红景天)

4. GaoYuanan  (高原安), purchase in China only

A healthcare product beneficial for easing mountain sickness; take it after you arrive in Tibet Autonomous Region. The main contents of Gao Yuanan are Ginseng, Rhidiolae, Ginseng fruit, codonopsis pilosula, Poria cocos, Plantain herb, Semen coicis, Astragalus and Semen boitae. You can buy either the capsule or pellet or granule. The effective would be the best if you take it one day beforehand and continue it for another three days after in Tibet Autonomous Region. It can help ease the headache, dizziness, cyanotic lip, palpitation and shortness of breath.  

GaoYuanan  (高原安)

5. Ibuprofen

A study published in 2012 in the Annals of Emergency Medicine by Dr. Grant Lipan, a professor of emergency medicine at Stanford University School of Medicine and a climber, recommends that taking a few ibuprofen tablets can prevent and alleviate the symptoms of AMS. Lipman says, "Ibuprofen can prevent 26% of cases of altitude sickness and help people who are without symptoms to stay without symptoms."

Prior to the study, recommended medications for acute mountain sickness (AMS) included dexamethasone and acetazolamide or Diamox, a prescription-only drug. Now add ibuprofen to the list of altitude cures. Ibuprofen has lots of plusses; it is fast-acting, cheap, readily available, and quickly absorbed by the body. Both dexamethasone and acetazolamide have adverse effects and require a doctor's prescription, whereas ibuprofen has few side effects except for an increased risk of gastrointestinal and kidney problems in users who are dehydrated and it is availavle over the counter from your pharmacy. As we ascend to higher altitudes, our bodies adjust to decreased oxygen in the air and reduction in air pressure, which leads to a swelling of the brain in some climbers. This allows fluid to build up in the brain, putting pressure on cranial nerves and causing headaches, dizziness, and the other symptoms of altitude sickness.

Ibuprofen, an anti-flammatory drug, decreases the swelling, lowering the risk of headaches and helping the body to adjust to an oxygen-deprived environment.

6. Nifedipine

This drug is normally used to treat high blood pressure and angina, but also seems able to decrease the narrowing in the pulmonary artery (pulmonary vasodilation) resolving the pulmonary hypertension responsible for the high pressure leak in the lungs caused by low oxygen levels, thereby improving oxygen transfer. It can therefore be used in the treatment of HAPO, though unfortunately its effectiveness is not anywhere as dramatic that of dexamethasone in HACE. Oxygen saturations gusually improve slightly after administration of nifedipine. The dosage is 20 mg of long acting nifedipine, six hourly.

Nifedipine can cause postural hypotension; a sudden lowering of blood pressure so the patient has to be warned to get up slowly from a sitting or reclining position. It has also been used in the same dosage to prevent HAPO in people with a past history of this disease.

7. Frusemide

It may clear the lungs of water in HAPO and reverse the suppression of urine brought on by altitude. However, Frusemide can also lead to collapse from low volume shock if the victim is already dehydrated. Usage of frusemide without medical supervision is not routinely recommended. The treatment dosage is 120mg daily.