The firm said people were having less sex at the start of the pandemic last year, which was due to a 'manifestation of anxiety'.
But it reported a 'double-digit' increase in sales of Durex - a leading condom brand - in the first quarter of 2021, compared to one year ago.
Reckitt also said sales jumped last summer when social distancing rules were relaxed.
Bosses say they expect this trend to follow elsewhere as other countries relax social distancing measures, providing more of an opportunity for consumers to use such products.
And it's not just condom sales that have been affected by the pandemic.
While the demand for health products dropped because people weren't stocking up on cold and flu medicines at the same rate as before, products like Lysol and Dettol saw strong sales figures as shoppers' hygiene habits improved.
Chief executive Laxman Narasimhan said: "Demand for Lysol and Dettol continues to be strong as consumers remain vigilant to the spread of the virus and see use of our products, and improved hygiene habits, as a way of protecting their health and regaining normality in their lives.
"As is to be expected, the underlying drivers of near-term demand for disinfectant products are dynamic, with countries around the world at different stages of the pandemic, and we are therefore closely tracking shifts in consumer behaviour to understand supply-and-demand trends.
"Our health business is seeing improved trading in sexual wellbeing, very strong growth in Gaviscon and improved execution overall.
"Meanwhile, we expect the difficult current market conditions for our cold and flu relief products to improve over time.
"In nutrition, trading continues to be strongly affected by the closure of the Hong Kong border, although we are beginning to annualise the impact of this."
Laura Hoy, an analyst at Hargreaves Lansdown, said in a statement: "While vaccine rollouts are making a return to normalcy look possible, some pandemic-related trends look here to stay and the public's new obsession with hygiene is one of them."
She added: "Dettol sales were strong, though they were buried under poor over-the-counter medication sales in the group's Health division.
"This shouldn't last long, though, as the next cold and flu season is likely to hit much harder as people should have more contact with each other."
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