I am not a doctor, but I am a former sprinter in the Olympic reserve squad, so I do have a certain knowledge of physiology. Some of it my coaches put into my head generously, and I added to it later out of my own curiosity and a certain necessity — at 21, for instance, I set off alone for my first two 7000-metre peaks. It is fashionable now to argue that only a doctor may speak aloud about physiology and pharmacology, so stones will certainly be thrown at this article, but I am ready for constructive criticism. Let me say in advance that I am writing this so you can show it to your many specialists: let them criticise it and prescribe you whatever they think right, and I will be waiting for you in the mountains!)))
People often ask me which medicines can treat altitude sickness. This article is my attempt at a full answer. We will cover the first-aid kit for a climb separately. First of all, remember that the best remedy for altitude sickness is acclimatisation, and that subject too deserves an article of its own. Here we will look at the main drugs that, in our view, can add a little comfort in the mountains. That adaptation to high altitude can be speeded up with medication is hardly news any more. Some climbers compare it with the use of doping in sport. Others naively suppose that such drugs can replace training and an acclimatisation programme. And there are those who have simply never thought about it. Unlike doping, though, this is not about a short-term boost at the expense of health; it is about supporting the body over a long period in the extreme conditions of high altitude. Altitude exposes the weak points in how the human body works, and adaptogens help those systems cope. A problem that complex cannot be solved with a single drug.
- Oxygen
- Aspirin
- Vitamins and micro- and macronutrients
- Adaptogens
- Hypoxen
- Mildronate
- Diacarb (Diamox)
- Viagra (sildenafil)
Oxygen against altitude sickness
The best medicine for altitude sickness is oxygen! Only a handful of people in history have climbed Everest without it, while some, using it to the maximum, contrive to climb Everest in as little as two weeks, spending no time on acclimatisation at all. But using oxygen in the mountains is not simple. There are two fundamentally different kinds: medical oxygen, in small low-pressure canisters of 300-400 ml that look rather like deodorant, and mountaineering oxygen, in 2-4 litre cylinders at high pressure. The medical kind gives you up to a hundred breaths and relieves the signs of moderate altitude sickness. Many guides are sceptical about it, but in our experience the effect is real and obvious. A large mountaineering cylinder lets you, for instance, make a full ascent of Elbrus with oxygen, avoiding any manifestation of altitude sickness, even if you arrived from the city today. But you cannot take oxygen into every country, even the medical kind, and transporting it is difficult, so slipping a canister or two into your mountain first-aid kit is not going to work.
Aspirin against altitude sickness
It thins the blood. There are other preparations, but aspirin-cardio at a dose of 80-100 mg, particularly the enteric-coated form, is something I take routinely in the mountains — although what worries me more is the possibility of clots, given a haemoglobin of nearly 200, but that is personal. You can also thin the blood with vitamin C, though most of the specialist medical research recommends aspirin specifically.
Vitamins and micro- and macronutrients against altitude sickness
There is no room in this article to set out the many facts about vitamins, but a deficiency of vitamin B12, for example, lowers a patient’s haemoglobin, and folic acid is an important element in the formation of blood. The various types of hypovitaminosis cause weakness, breathlessness, rapid fatigue, poor sleep and slow recovery after exertion. Going into the mountains with that set of symptoms will not be much fun, will it?
So it is worth taking a course of multivitamins before an expedition, and reducing the risk of any hypovitaminosis as far as possible. That matters most before long and demanding expeditions, of two weeks and more. For easy climbs — for instance a climb of Elbrus from the south, where the food is proper and the number of days on the mountain is kept to a minimum — it applies rather less.
Note that physical exertion increases your need for vitamins, and that arranging proper nutrition in the mountains is difficult or impossible.
On micronutrients: potassium and magnesium play an important part in keeping the heart healthy. When the body has enough of them, the cardiovascular system works without faults. Among the effects potassium and magnesium have in the human body are: regulating the generation of cardiac impulses, maintaining the normal metabolism of the myocardium (the heart muscle), improving the contractile function of the myocardium and of the muscles throughout the body, maintaining the elasticity of blood vessel walls, reducing the viscosity of the blood and preventing the development of clots. Potassium plays a key role in regulating the water and salt balance and the heart rhythm. Most potassium, roughly 98%, sits inside the cells and is needed for muscle tissue to work normally, including the heart muscle. Magnesium, for its part, affects the stable working of the nervous system and the normal functioning of the muscles. Together with potassium, magnesium improves heart rhythm and vascular elasticity, reduces swings in arterial pressure, prevents muscle spasms and has a calming effect on the nervous system. So, as an athlete, I recommend Panangin or its equivalents — a thing tested by time.
On iron: every molecule of haemoglobin contains an atom of iron; without enough iron, haemoglobin will not be produced. And then acclimatisation will not happen, however long the acclimatisation programme you follow. So vitamins containing iron matter a great deal, even if your diet is balanced.
Adaptogens against altitude sickness
This is an even bigger subject than vitamins. I will not weary you with long accounts of raised immunity, endurance, better sleep and the rest — you can read all that on Wikipedia without me. I will say only that I am an atheist and do not believe in mumijo or in Tibetan-African-Peruvian potions. What I can say for certain is that I have seen problems caused by «miracle supplements» more than once, so I strongly recommend not experimenting on yourself in the mountains, where nature will give you quite enough to deal with as it is. Eat the potions of the Tibetan lamas and drink the nectar of the gods at home before a run: treatment in the mountains is expensive, and sometimes impossible.
I am also too lazy to swallow extra tablets and drink mixtures, so I do not take ginseng, schisandra, rhodiola rosea, eleuthero, hawthorn or the rest of the classics.
Hypoxen against altitude sickness
A drug developed by our own scientists, which increases the efficiency of tissue respiration under hypoxia, particularly in organs with a high metabolic rate: the brain, the heart muscle, the liver. A number of experiments published in medical journals report strong results. I have no personal experience of using it; out of a thousand clients only a handful have taken it, so I will not comment on how well it works in the mountains, but I will try it on my next expedition.
Mildronate against altitude sickness
According to the manufacturer, the drug normalises the energy metabolism of cells subjected to hypoxia and supports the energy metabolism of the heart and other organs. I have heard many positive reports, but I noticed no effect on myself, though I tried it twice in the mountains and did several courses at sea level during intensive training. Nor did clients of mine who took it above 7000 metres perform any differently from those who took nothing. One thing is reassuring: doctors say no serious side effects have been found.
Diacarb against altitude sickness
The most popular tablet among climbers. A modern, evidence-based drug which will not protect you from altitude sickness, but will reduce its symptoms. It is acetazolamide, to give it its other name. A mild diuretic which acidifies the blood, which in turn increases your breathing and so speeds up acclimatisation. One of the advantages of Diacarb is that it does not mask the symptoms of altitude sickness, which means you will not miss a severe degree of hypoxia. Doctors recommend taking Diacarb at a dose of 250 mg every 12 hours at the first symptoms of mild altitude sickness: headache, loss of appetite, nausea, lethargy, weakness. It is recommended for no more than 3 days; if you are still gaining altitude after that, take a day off and then continue. Taking Diacarb leads to fewer symptoms and to milder forms of altitude sickness. Are there side effects? There are, and they are fairly harmless: tingling in the fingers, feet and face, a change in taste, excessive urination and blurred vision (rarely). When the drug is stopped, the side effects disappear.
Viagra (sildenafil) against altitude sickness
And now the biggest and most interesting section: the legends about Viagra in the mountains!
Altitude sickness is a serious condition caused by reduced oxygen availability, a consequence of the low atmospheric pressure at high altitude. Many deaths have been described from vascular thrombosis, haemorrhage and heart failure in people who were in the mountains. There is even the concept of the «death zone», beginning at an altitude of 6500-7000 metres above sea level.
Arguments about the effectiveness of sildenafil (Viagra) in treating altitude sickness and about its ability to increase physical performance at high altitude have been running for more than 10 years. Recently that discussion was given fresh impetus by a political scandal in South Korea which ended in the impeachment of President Park Geun-hye. One strand of the investigation was the discovery of a bulk purchase of Viagra by the presidential administration. The official explanation was that the drug was used to treat altitude sickness in the president’s aides during their visit to Kenya, Uganda and Ethiopia, which lie at an altitude of 1-2 kilometres above sea level. Interestingly, Korean doctors also prescribe sildenafil and its equivalents to climbers, since they help with adapting to conditions at altitude. The whole story may raise a smile, but for people who spend a lot of time at high altitude it is a serious question.
Viagra and sport
Several studies have been carried out to determine the effect of sildenafil on the physical performance of athletes under low-oxygen conditions. The results showed that sildenafil improves the function of the cardiovascular system and increases arterial oxygen saturation when oxygen content is low. Viagra can therefore be used not only to improve sexual function but also to improve physical performance in high-altitude conditions.
Some people may take this for a joke, so here are extracts from the scientific papers on the subject:
Sildenafil increased exercise capacity during hypoxia at low altitudes and at Everest base camp: a randomised, double-blind, placebo-controlled crossover trial.
Background: Alveolar hypoxia causes pulmonary hypertension and increased right ventricular vascular resistance, which may impair exercise capacity. The phosphodiesterase-5 inhibitor sildenafil is reported to cause pulmonary vasodilatation.
Objective: To investigate the effect of sildenafil on exercise capacity in hypoxic pulmonary hypertension.
Design: Randomised, double-blind, placebo-controlled crossover trial.
Setting: University Hospital Giessen, Giessen, Germany, and base camp on Mount Everest.
Participants: 14 healthy mountaineers and trekkers.
Measurements: Systolic pulmonary artery pressure, cardiac output and arterial oxygen saturation at rest and during assessment of maximum exercise capacity on a cycle ergometer 1) while breathing a hypoxic gas mixture with a 10% fraction of inspired oxygen at low altitude (Giessen) and 2) at high altitude (Mount Everest base camp).
Intervention: Oral sildenafil, 50 mg, or placebo.
Results: At low altitude, acute hypoxia reduced arterial oxygen saturation to 72.0% (95% CI, 66.5% to 77.5%) at rest and 60.8% (CI, 56.0% to 64.5%) at maximum exercise. Systolic pulmonary artery pressure in participants taking placebo rose from 30.5 mm Hg (CI, 26.0 to 35.0 mm Hg) at rest to 42.9 mm Hg (CI, 35.6 to 53.5 mm Hg) during exercise. Sildenafil, 50 mg, significantly increased arterial oxygen saturation during exercise (P = 0.005) and reduced systolic pulmonary artery pressure at rest (P < 0.001) and during exercise (P = 0.031). Sildenafil also increased maximum workload (172.5 W (CI, 147.5 to 200.0 W)) compared with placebo (130.6 W (CI, 108.8 to 150.0 W)); P < 0.001) and maximum cardiac output (P < 0.001). At high altitude, sildenafil had no effect on arterial oxygen saturation at rest or during exercise compared with placebo. Sildenafil did, however, reduce systolic pulmonary artery pressure at rest (P = 0.003) and during exercise (P = 0.021), and increased maximum workload (P = 0.002) and cardiac output (P = 0.015). At high altitude, sildenafil worsened existing headache in 2 participants.
Limitations: The study did not examine the effect of sildenafil on exercise tolerance under normoxic conditions.
Conclusion: Sildenafil reduces hypoxic pulmonary hypertension at rest and during exercise while maintaining gas exchange and arterial pressure. According to the authors, sildenafil is the first drug shown to be able to increase exercise capacity under severe hypoxia both at sea level and at high altitude. https://pubmed.ncbi.nlm.nih.gov/15289213/
Sildenafil inhibits hypoxaemia and pulmonary hypertension induced by high-altitude acclimatisation
Abstract: Exposure to high-altitude conditions causes pulmonary hypertension to develop, which can lead to life-threatening states. In a randomised, double-blind, placebo-controlled study, the effects of oral sildenafil on pulmonary hypertension induced by high-altitude acclimatisation, and on gas exchange, were examined in healthy subjects. Twelve subjects (sildenafil [SIL] n = 6; placebo [PLA] n = 6) were exposed to altitude for 6 days at 4,350 metres. Treatment (3 x 40 mg/day) began 6-8 hours after arrival from sea level at high altitude and was maintained for 6 days. Systolic pulmonary artery pressure (echocardiography) increased at high altitude before treatment began (+29% compared with sea level, p < 0.01), then normalised on sildenafil (-6% compared with sea level, NS) and remained raised on placebo (+21% compared with sea level, p < 0.05). Pulmonary acceleration time fell by 27% in the placebo group, compared with 6% in the sildenafil group (p < 0.01). Cardiac output and systemic arterial pressure increased on exposure to high altitude, then fell similarly in both groups. Pa(O(2)) was higher, and the alveolar-arterial oxygen difference smaller, in the sildenafil group than on placebo, both at rest and during exercise (p < 0.05). The fall in maximum oxygen uptake on exposure to high altitude was smaller in the sildenafil group than on placebo (p < 0.05). Sildenafil protects against the development of pulmonary hypertension induced by high-altitude acclimatisation and improves gas exchange, limiting altitude-induced hypoxia and the fall in physical performance. https://pubmed.ncbi.nlm.nih.gov/15516532/
Sildenafil for the treatment of high-altitude hypoxaemia
Abstract: Exposure to high-altitude conditions causes alveolar hypoxia and induces pulmonary hypertension (PH), with a consequent limitation of exercise capacity. To assess the effect of sildenafil on haemodynamic and clinical parameters and on aerobic performance, a study was carried out on 12 young, healthy, unacclimatised subjects (6 received sildenafil 40 mg 3 times a day, and 6 received placebo) at sea level and at high altitude. Systolic pulmonary artery pressure increased at high altitude but normalised on sildenafil. The fall in maximum oxygen uptake on exposure to high altitude was significantly smaller on sildenafil than on placebo. Improving the pulmonary circulation with sildenafil safely protects against pulmonary hypertension caused by high altitude and improves gas exchange. https://pubmed.ncbi.nlm.nih.gov/15516532/
Sergey Baranov, 2023