Tips & Tricks - GarwelGarwel/KerbalHealth GitHub Wiki

Here are some tips how to keep your kerbals healthy with Kerbal Health. They are based on default settings.

Consider mission duration

If your mission is short, i.e. less than about 7 days, you don't really need to worry about health, because your kerbals can make it. It is more than enough to visit Mun. In other cases you may decide to add some extra delta V to reach your destination and return in time.
Use high-level kerbals

Kerbals' maximum health increases with level: new recruits have 100 Health Points (HP) while five-star veterans have 150. It makes sense to take kerbals with more HP for longer missions. Remember that tourists are always level 0!
Let your kerbals rest

Kerbals need to restore their health after each mission. They gain +5 HP per day when not assigned, so a recuperation may take up to 30 days for a very exhausted high-level kerbal. Make sure your astronauts are healthy before you launch them to space again.
Give'em space!

Confinement is the single most important factor affecting your kerbals' health. The effect of this factor is proportional to the number of crew (including tourists) per available living space. Some parts are more spacious than the others; bigger and more expensive parts are generally better as well as those solely dedicated to habitation.
Stay connected

Chatting with mission control, receiving messages from family, watching your favorite space operas, and sharing pictures from interplanetary space is good for your health, according to the Kerbal Health Institute. Give your kerbals this opportunity by ensuring that the vessel is connected to home.
Loneliness is bad—or badass

Kerbals hate being alone, so much so that they get sick if left without crewmates for long. Although in most cases leaving a seat vacant will be more useful, very long missions will actually benefit from having more than one astronaut on board. This factor does not affect badass kerbals (such as Jebediah), who don't mind spending their entire mission in complete loneliness.
Standing firmly on the ground

Microgravity has negative long-term effects on kerbals' health, taking 0.5 HP per day whenever they are in free fall (i.e. in orbit or sub-orbit) or just on a very, very small celestial body. Minmus or Gilly count as such bodies, so landing there won't help your kerbals. Most other bodies provide enough gee force (i.e. at least 0.1 g) for normal functioning of little green organisms.
Keep EVAs short

Going on EVA is a serious challenge for one's health, whether it is in the void of space, in a toxic atmosphere of Eve or under Kerbin's rains and snow (although the latter is just slightly better). Prolonged EVA are also bad for long-term health, because the EVA suit provides very little protection against radiation. Actually, your kerbal may die if he/she has to spend more than a few days EVA. So try to do all your activities quickly, travel in pressurized rovers, and never ever abandon your guys and gals on a planet's surface.
Use parts with factor multipliers

Some parts (in stock game as well as in supported mods) provide multiplier bonuses to factors. For instance, a Hitchhiker Container lowers the effect of the Confinement factor by 60% for up to 4 kerbals. It means that if, for instance, you put 3 kerbals in the Hitchhiker (1.6 living space), they will lose 6 x (3 / 1.6) x 40% = 4.5 HP per day due to crowdedness. Note that it only affects one specific factor and, if your vessel has more than 4 kerbals, the multiplier's effect will be scaled down. You can see parts' multiplier stats in the Editor. Just remember to activate relevant health modules and have enough EC!
Recuperation bonuses can make your kerbals immortal (well, not really)

Some advanced parts, including the stock Cupola, provide opportunities for kerbals to recuperate and restore their health. A 1% Recuperation bonus means that every affected kerbal will restore 1% of their lost health every day. So, if your kerbal has 70 HP out of 120, they will restore (120 - 70) x 1% = 0.5 HP per day with this bonus. If you have enough parts with such bonuses and your vessel's design is good enough, you can actually make kerbals restore some health during a mission. The health will never reach 100% (because you still have negative factors), but it can stabilize on a certain acceptable level. You can see this level (if there is one) in the Health Report in the VAB/SPH window after → sign. Recuperation usually affects the whole vessel's crew, but some mods' medibay parts only affect their dwellers.
Mind the radiation

Radiation is not your friend! Whenever your kerbals are a mission, their accumulated dose is increasing, lowering their maximum possible HP. If your mission is long, lies in interplanetary space and/or in above the magnetosphere, make sure you use enough radiation shielding to protect against the nasty rays. Crew pods are capable of being reinforced with some shielding (some are better than the others), but you can add more with construction panels, heat shields, and mk3 cargo bays.
Always have Plan B

As in the real-world spaceflight, many things are unpredictable in Kerbal Health. Your kerbal can fall sick or have an unfortunate accident that may put your entire mission at risk. Moreover, some initially mild health conditions can deteriorate into very dangerous ones. Sometimes you can insure against it by having enough marginal health bonus, but sometimes you will have to consider aborting the mission and returning home before it's too late.