No decision has been made on a return date and no replacement has been named ahead of the second test in Colombo starting on Friday.
Shamsi, playing in his second test, returned match figures of four for 128 in the first game in Galle, where Sri Lanka routed South Africa by 278 runs inside three days.
The tourists have two other specialist spinners on the tour in left-armer Keshav Maharaj and uncapped leg-spinner Shaun von Berg.
South Africa also play five one-day internationals and a single Twenty20 match in Sri Lanka. Shamsi was included in the squads for both formats.
First Published: July 16, 2018, 9:09 PM IST