Medical Astrology indicates, the planetary influences which cause the various diseases, afflictions and accidents. It gives a clear picture of planets and its relation to disease, what disease will be produced under different planetary conditions, the duration of such diseases and whether or not they would prove fatal. Sickness in its various forms is caused through the differently composed afflictions of planets in the various signs of the zodiac & houses in the horoscope.
To have sound constitution and robust health, the lagna and its lord should be strong and the lord of 6th should be weak. Astrology and Medicine are intimately linked in as much as the science of healing, forms an important part of remedial astrology. Sun is a natural atamkaraka and gives health and energy. It should be strong and free from malefic influence (especially of the Saturn or Rahu) to give good health. Moon the planet of mind should also be frees from affliction for a clear and sound thinking.
In Astrology 6th, 8th and 12th houses are dusthanas. Malefics in these places are not good for health. 6th house is of diseases and the 6th lord does give ill-health during its dasal bhukti. In any chart look to the planet in the sixth from lagna and Moon, lords of 6th and the sign containing 6th house. These all combined together will give a clue about the disease and the part of the body affected by that disease.
Besides these three trik houses, even the other houses if badly afflicted and containing planets badly afflicted give specific diseases governed by those houses / signs and the planets contained in them. Such diseases are normally experienced during dasal bhukti of the afflicting planet(s) having sambandha with such a planet. The gochara of an afflicted planet is causative of a disease since a disease is caused when a planet is in an unfavourable position in gochara and its dasa / bhukti is running, for example, an affliction to first house in a chart and Aries impairs the brain and nervous system causing various diseases from headache to insanity and accidents involving the head and brain.
An affliction to sign Cancer and the 4th house will cause mental diseases like lunacy, retardation, dullness and also emotional diseases like fits, epilepsy, phobias and coma etc. An affliction to 5th house results in aberration of mind, schizophrenia, paranoia and perversion etc.
If the lagnesh is in 6th, the 8th or the 12th, especially the 6th, it is an indication that the native will be sickly. The matter becomes worse if lagnesh is aspected by a malefic whereas the aspect of a benefic gives a boost for good health. Malefics in dusthanas are not good for health. The dasa of a planet in the 2nd or the 7th (maraka houses) from lagna or chandralagna can also bring ill health. Jupiter in the 6th or aspecting the 6th gives good health. Jupiter with Moon or in the 5th or aspecting the Moon or the 5th is good for mental health. Sage Satyacharaya says that if the lord of 9th aspects the 6th and the 8th, there will be good health.
Moon with Saturn causes a weak physique, a worried mind, poverty and liability to false charges unless Saturn is the lord of lagna or is well aspected by Jupiter. Moon with Rahu or Kethu, especially the Rahu, is not good for general health or mental balance. New Moon, being a malefic, is good in 3rd, 6th and the 11th.
6th house represents the house of diseases. Saturn or Rahu in this house though good for prosperity, causes illnesses. If the 6th house is Virgo, disease is of the stomach or bad digestive power on account of poor secretion of gastric juices or diarrhoea or dysentery. 6th house denotes diseases, 8th house denotes long illness that may be fatal in character, whereas, 12th house indicates confinement in a hospital.
Venus in 6th (except, perhaps, when in Libra or in an adhiyoga configuration) is bad to cause venereal diseases especially if it is afflicted by Saturn or Mars or any node. Moon is a watery planet and if conjoined with or aspected by fiery Mars, it may cause instability of mind and may make the native violent in mind, furious, abusive, malicious and treacherous.
Saturn's affliction to Moon makes one gloomy and melancholic and native becomes dull, impertinent and obstinate. Mercury governs one's intelligence and thinking. If it is afflicted, especially by its enemy, Mars, his thinking is badly affected and the native is likely to fly in fury occasionally and use incoherent language.