Hair drug tests (and the other drug testing modalities, for that matter) do not routinely test for the presence of penicillin. The drugs commonly tested for are:
1. THC (marijuana)
2. Cocaine
3. Amphetamines & methamphetamines (including "rave drugs" like ecstasy)
4. PCP ("angel dust")
5. Opiates (morphine, codeine, and heroin)
Expanded drug tests are sometimes used, and check for these additional drugs:
6. Benzodiazepines (Valium, Ativan, Xanax, etc.)
7. Synthetic narcotics (hydrocodone, propoxyphene, oxycodone)
8. Methadone