The worries over the new sugar tax raid were compounded by Brexit pains for the drinks maker, which is also behind the Tizer and Rubicon brands.
The firm said the post-EU referendum weaker pound, if sustained, will lead to higher costs, which could amount to a £3 million to £4 million hit in 2017.
Separately, the company said sales dipped to £125.6 million in the six months to July 30.
Pre-tax profit edged up to £17 million from £16.9 million. Shares dropped 5.5p to 517p following the update.
The firm is planning to lay off staff as part of a restructuring, with about 90 jobs likely to be cut in commercial and supply chain functions.
White said: “Market conditions remain volatile and somewhat unpredictable — however, assuming a strong trading performance in the key festive period, we remain on track to deliver profit (before tax and exceptionals) slightly ahead of last year.”
Shore Capital analyst Phil Carroll said: “We believe the timing of the period end for the interims has not been favourable for the company to some extent given how poor the weather was in the important summer months of June and July.”
