A compound of Formula I: or a pharmaceutically acceptable salt thereof, for use in the acute or prophylactic treatment of migraine headache or cluster headache in conjunction with one or more agents selected from: an anti-migraine agent; a 5-HT 1B/1D agonist; a 5-HT 1D agonist; a 5-HT 1F agonist; a cyclooxygenase inhibitor; a non-steroidal anti-inflammatory agent or cytokine-suppressing anti-inflammatory agent; a glucocorticoid; and an analgesic; wherein: X is selected from -C(R 8)= or -N=, wherein R 8 is hydrogen, F or CN; R 1 is selected from the group consisting of: C 1-4 alkyl, cyclopropylmethyl, cyclobutylmethyl and [1-(trifluoromethyl)cyclopropyl]methyl, each of which is optionally substituted with one or more substituents as allowed by valence independently selected from the group consisting of: F and hydroxy; R2 is selected from hydrogen and methyl; when R 2 is hydrogen then R3 is selected from hydrogen, F or Cl; R4 is selected from hydrogen, F or Cl; R 5 is hydrogen; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, F or Cl; except that at least two of R 3, R 4, R 6 and R 7 must be F or Cl unless R 3 is F in which case R 4, R 6 and R 7 may all be hydrogen; and if R 4 is Cl then R 7 cannot be Cl; when R 2 is methyl then R3 is selected from hydrogen, methyl, F, Cl, or Br; R 4 is selected from hydrogen, methyl, F or Cl; R5 is selected from hydrogen or F; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, methyl, F or Cl; except that if R 5 is F then at least three of R 3, R 4, R 6 and R 7 must be F; and if R4 is methyl or Cl then R 7 cannot be methyl or Cl. an anti-migraine agent; a 5-HT 1B/1D agonist; a 5-HT 1D agonist; a 5-HT 1F agonist; a cyclooxygenase inhibitor; a non-steroidal anti-inflammatory agent or cytokine-suppressing anti-inflammatory agent; a glucocorticoid; and an analgesic; X is selected from -C(R 8)= or -N=, wherein R 8 is hydrogen, F or CN; R 1 is selected from the group consisting of: C 1-4 alkyl, cyclopropylmethyl, cyclobutylmethyl and [1-(trifluoromethyl)cyclopropyl]methyl, each of which is optionally substituted with one or more substituents as allowed by valence independently selected from the group consisting of: F and hydroxy; R2 is selected from hydrogen and methyl; when R 2 is hydrogen then R3 is selected from hydrogen, F or Cl; R4 is selected from hydrogen, F or Cl; R 5 is hydrogen; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, F or Cl; except that at least two of R 3, R 4, R 6 and R 7 must be F or Cl unless R 3 is F in which case R 4, R 6 and R 7 may all be hydrogen; and if R 4 is Cl then R 7 cannot be Cl; R3 is selected from hydrogen, F or Cl; R4 is selected from hydrogen, F or Cl; R 5 is hydrogen; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, F or Cl; except that at least two of R 3, R 4, R 6 and R 7 must be F or Cl unless R 3 is F in which case R 4, R 6 and R 7 may all be hydrogen; and if R 4 is Cl then R 7 cannot be Cl; when R 2 is methyl then R3 is selected from hydrogen, methyl, F, Cl, or Br; R 4 is selected from hydrogen, methyl, F or Cl; R5 is selected from hydrogen or F; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, methyl, F or Cl; except that if R 5 is F then at least three of R 3, R 4, R 6 and R 7 must be F; and if R4 is methyl or Cl then R 7 cannot be methyl or Cl. R3 is selected from hydrogen, methyl, F, Cl, or Br; R 4 is selected from hydrogen, methyl, F or Cl; R5 is selected from hydrogen or F; R6 is selected from hydrogen or F; and R 7 is selected from hydrogen, methyl, F or Cl; except that if R 5 is F then at least three of R 3, R 4, R 6 and R 7 must be F; and if R4 is methyl or Cl then R 7 cannot be methyl or Cl.