What is the Karmic Effect of Harsh Speech? What are the karmic fruits/consequences of speaking harshly to others?
The mind &amp; body is disturbed, with agitation &amp; stress ('hell'). 

Friends may be lost or social status (such as a job) may be lost, which results in deficiency &amp; need ('hungry ghost'). 

Shame &amp; regret will eventually arise internally  (if the mind returns to a normal or 'human' state). 


  Pharusā, bhikkhave, vācā āsevitā bhāvitā bahulīkatā niraya­saṃ­vatta­nikā tiracchā­na­yoni­saṃ­vatta­nikā
  petti­visa­ya­saṃ­vatta­nikā. Yo sabbalahuso pharusāya vācāya vipāko,
  ­manus­sa­bhūtassa amanā­pa­saddasaṃ­vatta­niko hoti
  
  Harsh speech — when indulged in, developed &amp; pursued — is something that leads to (saṃvattanika) hell (niraya), leads to the animal birth (tiracchā­na­yoni), leads to the
  realm (­visa­ya) of the hungry shades (petti­). The slightest of all the results coming
  from harsh speech is that, when one becomes human (manus­sa), it leads to
  unappealing (amanā­pa­) sounds.
  
  AN 8.40 Vipaka Sutta