His Williams Formula One team said the 36-year-old had been given the all-clear by the FIA medical delegate following tests at the circuit on Thursday, a standard procedure following injury or sickness.
Massa went to hospital after Friday practise in Budapest but was then passed fit to continue on Saturday, when he experienced more dizziness.
The Brazilian was replaced for qualifying and the race by British reserve Paul di Resta.
The 7km Spa circuit is the longest, and one of the fastest, tracks on the calendar and this year's cars will be going quicker through the corners and subjecting the drivers to even more G-forces than before.
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Massa suffered near-fatal head injuries after being hit on the helmet by bouncing debris during qualifying at the Hungarian Grand Prix in 2009. The then-Ferrari driver spent several days in hospital in an induced coma after that incident.
(Reporting by Alan Baldwin; Editing by Keith Weir)
