Olbas for Children Inhalant Decongestant Oil Olbas for Children Inhalant Decongestant Oil is a gentle decongestant formula that gently clears up little blocked noses caused by cold & flu, catarrh, hayfever & blocked sinuses. Suitable for children as young as 3 months, it contains a mixture of essential pure plant oils which give off natural vapours to immediately clear nasal congestion & relieve painful sinuses.