Jan 25 (Reuters) - British tonic maker Fevertree Drinks forecast annual core profit to be at the lower end of its expectations, even as profit doubled in the second-half on strong performance in its U.S. market, offsetting materials' inflationary cost pressures.

The company, which manufacturers and sells drink mixers, said on Thursday that it now expected core profit for the year to be about 30 million pounds ($38.16 million), compared with its prior expectations of 30-36 million pounds.

($1 = 0.7861 pounds) (Reporting by Radhika Anilkumar in Bengaluru; Editing by Rashmi Aich)