On the other hand, the use of HAART for patients with TB may cause severe complications due to drug-drug interactions, and occasionally a temporary exacerbation of symptoms, signs or radiographic manifestations of TB. Such events or 'paradoxical reactions' that occur among 7 - 36% of HIV/TB co-infected patients treated with HAART may be secondary to immune restitution. These reactions may be particularly severe when HAART is started soon after the start of TB treatment.