The Lions face a tough schedule, playing all five of New Zealand's Super Rugby sides and a match against the Maori All Blacks in addition to the three tests in Auckland and Wellington.
Henry coached the Lions to a 2-1 series loss on their 2001 tour of Australia and four years later guided the All Blacks to a 3-0 series sweep over the famous touring side in New Zealand.
"There is huge pressure on the Lions," 70-year-old Henry said in comments published on ESPN's website.
"I know from my own experiences how much the players respect getting selected for the Lions. It is the pinnacle of their career. It is massive but they need to do well and I just wonder if the itinerary is suicidal. That is my concern."
New Zealand's Super Rugby sides have been dominating the competition and are unlikely to be a pushover for Warren Gatland's Lions team, as witnessed by the Waikato Chiefs' 40-7 demolition of Wales during their tour last June.
"They are playing New Zealand Maori, they are playing the five franchised teams -- and those five franchised teams have nothing to lose, no pressure on them at all, so they will fire everything at the Lions and take them on.
"Hopefully (the Lions) have the ability to overcome that.
"But really when you tour, you need to ensure some momentum is created by results and you just wonder how they are going to go into the test series with that itinerary.
"It is very demanding.
"You just want the Lions to do well because it is such a marvellous brand in world rugby and they need to do pretty well to maintain the potency of the brand, because it's huge for the southern hemisphere countries to have the Lions tour."
The Lions open the tour on June 3 against a New Zealand Barbarians side in Whangarei.
(Reporting by Ian Ransom in Melbourne; Editing by Sudipto Ganguly)
