EXHIBIT 23.1
 
               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS
 
    We consent to the incorporation by reference in the Registration Statements
(Form S-8 No. 333-07069, Form S-8 No. 333-59735 and Form S-8 No. 333-65919)
pertaining to the Employee Stock Purchase Plan, the 1994 Equity Incentive Stock
Option Plan, the Non-Employee Directors Stock Option Plan, the 1994 Equity
Incentive Plan and the 1998 Non-Officer Equity Incentive Plan of Inhale
Therapeutic Systems, Inc., and the Registration Statement (Form S-3 No.
333-20787) and in the related Prospectus of Inhale Therapeutic Systems, Inc. for
the registration of 1,800,000 shares of its common stock, and the Registration
Statement (Form S-3 No. 333-68897) and in the related Prospectus of Inhale
Therapeutic Systems, Inc. for the registration of 1,200,000 shares of its common
stock of our report dated January 22, 1999, with respect to the financial
statements of Inhale Therapeutic Systems, Inc. included in this Annual Report
(Form 10-K) for the year ended December 31, 1998.
 
                                          /s/ ERNST & YOUNG LLP
 
Palo Alto, California
March 29, 1999