Are Tennis players on the ATP and WTA tour allowed to take PAINKILLERS before or during the match?

The tour has set rules for drugs that are permissible for the players to take. If a tennis player is prescribed a drug by a doctor that is NOT on the list of permissible drugs then they appeal/inform the tour that they have to take the drug for whatever their medical issue is, and then with proof from the doctor they are allowed to take the drug while still participating in the tournaments. So in the case of the B12 injection shots, if it was for the sake of their health the tour cannot/should not argue with the drug being taken (with the exception of things such as steroids and marijuana). Players probably wouldn't take painkillers before their tennis match since it makes them kind of loopy and would make them ineffective against a professional athlete, but there are many instances in which players receive shots before their matches which nullify the pain rather than take a pill which would almost guarantee them losing, (but as long as the drug is acknowledged by the tour beforehand it's all fine).