Almost all shastras say that there should not be any malefics in the eighth house, otherwise the longevity of the native is severely curtailed. However, malefic such placed is either exalted or own house, then the longevity is not much affected. Along with the longevity of the native, this house also rule the longevity of relationships or marital ties. Malefics placed here can affect the marital harmony and longevity of the marriage. Among malefics, Mars’s placement is the worst placement and it goes by the name of Kuja dosa. This cause extreme troubles in marriage and the spouse might suffer death (if Mars is badly placed) or bad health.
Planets in the eighth house generally express their negative qualities. Though shastras classify planets as benefics and malefics, all planets are capable of giving good or bad results based on whether their negative or positive qualities are expressed. The positive qualities are displayed when a planet is well placed in exaltation or mulatrikona or own house or friends house and the negative qualities are displayed when a planet is debilitated or in enemies house. This must be kept in mind while analysing a bhava and it is specifically applicable to eight house as this house is the house of our weaknesses. Even if a malefic is placed here, it must be very strong, for favourable results, otherwise, the results can be extremely troublesome.
From the argala perspective, the planets in the eighth house shall have dhanargala on the 7th house, sukhargala on the fifth house and labhargala on the ninth house. Thus the significations of houses 5th, 7th and 9th are significantly influenced by the planets in the eighth house.
The placement of Moon in the eighth is condemned by most classics. This position of Moon goes by the name of chandrastama. For such positions of Moon, the native suffers with regards to the functional and natural significations of Moon. As moon govern the physical body and mind and its resistance to diseases etc., such position of Moon can cause chronic illnesses and also mental troubles such as depression etc.
Among all the planets the placement of Mercury in the eighth house is accorded high regards by all shastras. Mercury is treated as grandson by the karaka of the eighth house; Saturn and Mercury rarely give bad results if placed in eighth house, unless heavily afflicted. Such position of Mercury gives good health, long life; knowledge of occult; virtuous and gain wealth with his own effort.
Famous; Sudden gains (from lotteries or speculation or inheritence); Committed to his words
Angry; Defective eye sight; Weak constitution/ Health troubles; Head Injury; Loss of Wealth; Separation from kith & kins; Few children; Devoid of happiness; Disease of Anus; Suffer from Headache & Fever
Long life (only under benefic influences)
Fickle minded/ Restless/ suffer psychological troubles; Weak constitution and easily affected by dieases; Face adversities; Fear from enemies and Danger from watery places; Short life (more so if moon is afflicted and the eighth lord is also weak and afflicted)
Favourable (only under benefic influences)
Happy married life, Good health and Long-life
Eye diseases / Defective eye sight (BS, BJ); Short life (unless the eighth lord is strong); Afflicted body/ Suffer due to blood related diseases; Critical to others; Sickly; Infamous; Suffer poverty; Ugly; Sexual perversions; Sorrowful; Early death of father; Urinary diseases; Consumption (T.B.); Few children; Suffer rheumatism and shooting pains; Unsuccessful in his efforts; No support from others; Adversities in life; Devoid of marital happiness (this one of the conditions of Kuja dosa)
Long lived; Owner of a large area of land; Many children; Respect and honour in many ways and will get wide spread fame and reputation; Widely known for his qualities; Authority to award punishment (judge, magistrate etc); Wide spread reputation; Supporter of his family; Virtuous; Famous; Glorious; Powerful; Acquire wealth by favour of the king or by doing business; Enjoy the company of women
Long lived; Free from diseases; Saintly person; Learned; Well versed in Vedas & shastras
Will not live in paternal house; Loose morals; Short lived; Sinful; Illicit relationships; Suffer poverty & earn his livelihood by serving others
Happy; Long life (Venus rules over Mrtyunjaya mantra); wealthy, long-lived; owner of lands; Saravali says that such natives will be endowed with all kinds of comforts, very wealthy, like a king and happy, which is also supported by Chamatkar chintamani, which adds enjoyment of conveyances to the list.
Trouble to mother; Short life (more so if afflicted); Sickly; Have a devoted wife but he will be discontented; Base; Harsh speech; Tormented by debt
Long life (also dependent on the strength of the 8th lord)
UnfavourableIntimacy with low caste women; Earn by serving others; Defective eye sight; Limited number of issues; Unclean; Suffer from piles and other diseases of anus; Suffer poverty; Cruel minded; Devoid of good food; Unsuccessful in ventures; Loss of wealth; Devoid of company of friends; Sickly; Evil minded