The company sells five different doses of the drug in South Africa, four in capsule form. There is a stockout of the tablet form at company warehouses.
Novartis assured The Times that new stock will arrive in the country within days and the shortage resolved by 15 September at the very latest.
The tablet is likely to still be available at some pharmacies.
Ritalin is a prescription drug for children diagnosed with Attention Deficit Hyperactivity Disorder. It helps them concentrate at school.
There are other generic forms of Ritalin, currently available in South Africa.
The shortage of the Novartis low dose tablet is due to a paperwork and permit glitch in America.
Meanwhile, the Department of Health has sent out a letter to doctors telling them that there is shortage of Nevirapine syrup, which is given to babies born to mothers who have HIV. The letter asks doctors or nurses to prescribe AZT or another drug caled Lamuvidine instead.
Nevirapine is given to infants of HIV positive mothers to ensure they do not become HIV positive.
The Department of Health spokesman Joe Maila said: "Indeed we experience a shortage of Nevirapine syrup and it must be noted that shortage is not limited to South African but a global problem. However, we have advised clinicians in South Africa to switch to Zidovudine syrup."
He said: " Secondly, we made contacts with the other supplier and they have flown in Nevirapine syrup to South Africa and we are distributing the stock to our facilities"
The 100 ml of the syrup is expected back in facilities this week and 240 ml syrup will arrive in January.