Space Flight: Side Effects May Include


So let’s get started with a list of health effects that may be induced by weightlessness, radiation, decompression, and the hazards of spaceflight in general (I’ll edit top post based on comments):

In flight:

  • osteopenia (bone loss)
  • osteoporosis (severe bone loss)
  • muscle atrophy (loss of muscle)
  • motion sickness
  • discoordination
  • disorientation
  • perceptual illusions
  • nastigmus (rapid eye movement, like from making yourself dizzy)
  • nausea
  • nephrolithiasis (kidney stones)
  • difficulty urinating
  • urinary tract infection
  • flatulence
  • high blood pressure
  • reduced blood volume
  • allergic hypersensitivity
  • heart arrhythmia (abnormal heart rhythm)
  • fluid shifts
  • nasal congestion (stuffy nose)
  • facial edema (puffiness around the face)
  • elongation of the spine
  • headache
  • increased intracranial pressure
  • immunosuppression
  • myopia (loss of vision)
  • corneal damage (from FOD in the eye)
  • poor appetite
  • weight loss
  • sleep disturbances
  • fatigue
  • other signs of depression? (to be fair 4 out of 6 of these are also symptoms of weightlessness, so it’s hard to tell)

Return to ground:

  • orthostatic intolerance (trouble standing)
  • impaired exercise capacity
  • motion sickness
  • discoordination
  • disorientation
  • perceptual illusions
  • nausea
  • loss of balance while turning
  • nastigmus (rapid eye movement, like from making yourself dizzy)
  • back pain and nerve entrapment

UV damage (through windows):

  • sunburn
  • corneal damage
  • skin cancer

Low Dose Rate (Galactic Cosmic Radiation):

  • infrequent bright flashes in the visual field (from GCR hitting your eye)
  • cataracts
  • pancytopenia (too few blood cells)
  • myeloproliferative disease (too many blood cells)
  • leukocytopenia (immune system failure)
  • vascular damage
  • septicemia (infection of the blood)
  • cancer
  • death

High Dose Rate (Solar Energetic Particle Event, mostly for beyond LEO):

  • anorexia (loss of appetite)
  • sterility/infertility
  • depilation (hair loss)
  • erythema (rash)
  • tissue swelling
  • dermatitis
  • desquamation (skin falls apart)
  • membrane ulceration
  • fibrosis of the lung
  • nausea
  • liver congestion
  • impaired healing
  • loss of intestinal lining
  • indigestion
  • diarrhea
  • thickened saliva
  • cataracts
  • petechial hemorrhaging (small bruises caused by capillary rupture)
  • cerebral edema (swelling of the brain)
  • seizures
  • ataxia
  • discoordination
  • neural degeneration
  • immune collapse
  • sepsis
  • disseminated intravascular coagulation
  • cancer
  • death


  • hypoxia
  • decompression sickness (the bends)
  • nerve damage
  • paresis (tingling) of the extremities
  • paralysis of the extremities
  • High Altitude Cerebral Edema (brain swelling)
  • High Altitude Pulmonary Edema (lung fills with fluid)
  • trouble breathing
  • rapid breathing
  • increased heart rate
  • loss of consciousness
  • death


  • asphyxiation
  • petechial hemorrhaging
  • ruptured ear drum
  • hearing loss
  • hypothermia
  • ebullism (water vapor filling body compartments)
  • pneumothorax (air around the lung)
  • pneumopericardium (air around the heart)
  • air embolism (air in the heart)
  • lung trauma
  • sinus trauma
  • paresis (tingling) of the extremities
  • seizure
  • numbness of the extremities
  • vertigo
  • chest pain
  • emphysema (fluid in the lungs)
  • aphasia (inability to speak or understand speech)
  • blindness
  • loss of consciousness
  • death

Engineering Hazards:
Inhalation of toxic gases and dusts:

  • irritation of the nose and throat
  • sore lungs
  • dizziness
  • trouble breathing
  • headache
  • vertigo
  • respiratory acidosis
  • fibrosis of the lung
  • muscle twitching
  • bone loss
  • difficulty exercising
  • difficulty thinking
  • cancer
  • loss of consciousness
  • death

Fan noise:

  • loss of hearing
  • trouble sleeping

Loss of fans:

  • hypercarbia (too much CO2)
  • asphyxiation
  • loss of consciousness
  • death

P.S. Do we want the big scary medical jargon like you’d have on a pharma ad? Or should we keep this in plain language?
If you’re going to make an audio bit of this, I’d recommend just using the “weightlessness”, “low dose rate radiation”, and “fan noise” sections, everything else is a pretty rare threat or some kind of emergency.

Barratt M.R. and Pool S.L. Eds. Principles of Clinical Medicine for Space Flight. New York: Springer; 2008. ( ISBN: 978-0-387-98842-9 )


On fluid shifts:
There are three primary fluids we worry about for space flight induced fluid shifts.
In the veins: Blood (composed of serous fluid, conductor proteins, and red and white blood cells; produced in the marrow of the bones)
Out of the veins: Lymph (composed of serous fluid that leaks out of the windows of veins)
In the brain case: Cerebrospinal Fluid (produced in the ventricles of the brain and moves down into the spine)

The veins of the legs have valves which prevent back flow. Every time your leg muscles contract, the fluid is thus pushed up toward the abdomen and cannot return.

Lymph is absorbed by a collection system which has tubes running throughout the body spaces, the fluid is absorbed into lymph nodes where debris is removed and analyzed for pathogens (muscle contraction or massage can also push fluid into the lymph nodes). The nodes also act as valves, and the filtered fluid is returned to the blood circulation into veins through ducts just below the clavicle and also at mid thorax. So there is an enormous focus on fluid entering the middle of the body and being conducted away from the extremities. Without gravity to pull (or exercise to push) these fluids out of the middle area, the fluids tend to congest centrally and be pushed up into the head. The body has some sensors for maintaining fluid pressure (for instance, the blood sensors are at the top of the heart just before the aorta and just below the ears nestled around the jugular veins). After about a week in space, these sensors will tell the body to change the production rate for these fluids. Thus, by about 2 weeks, you will have less blood (settling at about 1 liter less than normal). This is part of why astronauts have trouble standing up after a long flight.

For the Cerebrospinal Fluid, there is a tendency for the drain port leading from brain to spine to be pinched closed (or at least more closed than normal). This has to do with the elongation of the spine causing the inelastic spinal cord to tug the brain slightly down into the foramen magnum, partly blocking flow. This is why pressure builds up behind the eye in some people. The extra pressure also squishes the brain. Furthermore, all the extra blood in the face area causes more lymphatic fluid to seep from the veins, that’s what typically causes the facial puffiness, sinus blockage, and nasal congestion.


And i thought doing risk assments for Socuts camping on active airfields was a nightmare.


For a pilot:

These three alone should have killed the space program. Everyone should just have said, “Nope.” But astronauts are awesome. Thank god for computer control nowadays.


Strong ultrasound may make your eyeballs vibrate,

Strong gamma will give your brain euphoria


A moon base/station 2 weeks of extreme baked, frozen

Running out of food/water = starvation/dehydration



LOX leak too much oxygen; muscle contractions - hands curl up.


Hmm, I’ve kind of tried to group most of the symptoms of various toxins together; though I’m sure I missed a few. A lot of the different symptoms for a toxic exposure overlap, so it might be good to have separate post to address specifics of each gas.


Oxygen Toxicity:

Normal O2 is around 16-17 kPa (in mountain towns) to 21 kPa (at sea level). On the ISS, 21 kPa is the normal set point as well. The shuttle had 24 kPa for normal operation. EMU (spacesuits) use 33 kPa.

The threshold level for O2 toxicity is about 50 kPa. Below this, no symptoms are apparent. Breathing 101 kPa (100% O2 at sea level) for more than 2 hours will begin to cause symptoms of toxicity. This toxicity is progressive and is caused by fluid build up in the alveolar sacs. The fluid comes from an irritation of the cells that compose the lining of the lung (immune response). This response is probably due to a build up of free radicals near the mitochondria of the lung cells. This irritation response is additive, if O2 breathing is interrupted with a more normal O2 level (an “air break”), the damage is postponed but will resume where it left off when 100% O2 is again applied. It takes about a day of recovery for the irritation to die down. At very high levels of O2 (achievable only in hyperbaric chambers) there is also neurological toxicity that can present.

These charts are only applicable to hyperbaric O2.
Neurologic Symptom Frequency of breathing 100% O2 at 284 kPa (2.8 atm):
Time till onset of symptoms depends on O2 pressure. At 607 kPA pO2 (6 atm), seizures can happen in minutes. Because these symptoms require higher than normal atmospheric pressure, they are unlikely to be encountered aboard spacecraft unless someone is being treated for Decompression Sickness.

Decreases in lung function (due to irritation of the alveoli) with breathing of 100% O2 at 202 kPa (2 atm):

As the exposure to O2 is reduced (or the pressure of O2 decreased), the time till drop in lung function increases, becoming infinity at ~50 kPa.

images and info source:
Norfleet W.T. Chapter 11: Decompression-Related Disorders: Decompression Sickness, Arterial Gas Embolism, and Ebullism Syndrome. In Barratt M.R. and Pool S.L. Eds. Principles of Clinical Medicine for Space Flight. New York: Springer; 2008. ( ISBN: 978-0-387-98842-9 )

references for images:
148. Clark JM. Oxygen toxicity. In: Bennett PB, Elliot DH (eds.), The Physiology and Medicine of Diving. London: WB Saunders; 1993:121–169.
150. Butler FK, Knafelc ME. Screening for oxygen intolerance in U.S. Navy divers. Undersea Biomed Res 1986; 13:91–98.



And the #1 cause of human death is birth.

Just a thought… many items on @faulx list above can be mitigated/balanced in favor of humans exploring and extending our circle to multiple locations. Would you rather live 85 years on Earth, or live 80 years while helping to extend the human presence to Mars and beyond.

(Not sure I said that correctly… had too much coffee today).


You said it just fine; And indeed nobody gets out of life alive


Yeah, the military runs into this problem with safety inspectors all the time. For instance, halogenated foams for fighting aircraft fires are “toxic” and inspectors complain about their environmental impact or long term health effects. But they seem to forget about the short term health and environmental impacts of a large aircraft burning uncontrollably where ever it might have crashed.

This effect is even more pronounced in combat. What’s more dangerous in a sea battle, a fire in the engine room threatening to knock out maneuverability or spraying the place down with toxic foam that might kill you in 20 years?

Space is dangerous. Given all the risks you have to take to operate so far from civilization, if you’re dying of something like cancer, it means you did everything else right. It’s just silly to let a distant (and increasingly treatable) medical risk like that stop you from operating in the here and now.


Blowing up the launch pad
Burning up on re-entry
Toxic smolder of plastics
Navigation errors -lost in Space
Cold thermal failure


Oh… those are all sort of spaceflight adjacent. I kind of see that as spaceflight done wrong.

I’ve got intermittent fan failure and the occasional burnt electronic part putting out toxic gasses because they’re kind of inevitable even if you do everything right. The same is true for slow decompression (can theoretically happen on EVA) and rapid decompression (can happen when struck by undetected hypervelocity impactors… especially in LEO).

So philosophical question: Should we put overdose symptoms into a drug label’s list of side effects?


Quite possibly … We put symptoms of ‘accidental’ contact or ingestion on chemical labels


Hmm, medicines these days are doled out in tightly controlled doses though. It would hard to use it wrong unless you are trying. Unlike with a lot of chemicals which are concentrated liquids or caustic powders, where accidental handling errors are more likely.

By analogy, early space flight was a lot like a concentrated chemical (needs warning label), but by the time tourists have access to space flight it should be more like a pill (has list of side effects).


If you put 100 people on a BFR as long as the air is ok it should be fine.


Meh real men don’t read the instructions anyway … till it goes wrong then we blame the instructions that we didn’t read/ignored :stuck_out_tongue:


Maybe a note at the bottom which says, “Improper use of this product may cause:”… along with an upside down equilateral triangle with a skull and cross bones in the foreground (along with other relevant chemical warning label symbols), followed by a list of the worst that could happen.

That’s gonna be a long list…