Second-quarter sales to end June 2021 rose 6% to GBP8.1bn, though revenue growth was much stronger at 15% if the effect of currency movements were stripped out.
Emma Walmsley, chief executive, said the positive momentum was expected to continue through the second half of the year with a meaningful performance improvement also expected in 2022.
Walmsley who has been under fire from activist investor Elliot Management for plans to separate the consumer healthcare business from the pharma division said the priority now was execution and unlocking the value of Consumer Healthcare.
Earnings per share fell by 39% to 27.9p in the second quarter, while over the half-year there was a 36% drop to 49.4p.
Walmsley said that its guidance this year is in spite of sales of Shingles vaccine Shingrix recovering more slowly than expected.
Inoculations have been affected by people not being able to go to a clinic due to coronavirus restrictions, though with vaccinations programmes rolling out Glaxo expects demand for Shingrix to pick up during the second half of the year.
Glaxo added that income from Covid-19 sales had reached GBP276mln in the first half, most of which were pandemic adjuvant sales.
Covid-19 sales will account for 4-6% of adjusted EPS growth, it added, but its forecasts going forward do not include anything for the success of any virus-related products under development.
The quarterly dividend is maintained at 19p, with 80p still expected for the full year.
Shares dipped to 1,394p.