Retail giant Conforama withdrew the chairs, on sale since 2005, in July after a doctor warned they could be linked to an outbreak of eczema in one of his patients, spokeswoman Isabelle Hoppenot said.
She said some of the chairs, made by the Chinese company Link Wise, contained too much of an anti-mould substance, and that "in some people they can cause allergic reactions."
French newspaper Le Parisien said a dozen people had been hospitalised in a serious condition after buying the chairs.
Conforama has received letters of complaint from some 400 customers seeking damages, and some 800 buyers have received an exchange or refund, the spokeswoman said.
According to Conforama, the Chinese manufacturer placed several anti-mould packs inside the chairs to protect them from damage during the monsoon.
The retailer has written to the 38,000 people who purchased one of the chairs between 2006 and 2008 alerting them to the risk of allergy, but has not recalled the items.