Mixing Adderall and methadone together without a doctor’s instruction can be dangerous. While some patients can and should be on the medications together, this should always be done with medical supervision.
Adderall & Methadone
Adderall and Methadone are medications used to treat two different conditions - namely ADHD and substance use disorder. Some patients may have both conditions and require treatment for both, which means they may be on these two medications at the same time. While this certainly can be done safely, it should be done under medical supervision.
Adderall is a brand name for a medication combining the drugs dextroamphetamine and amphetamine. It is primarily used to treat ADHD in adults and children. Adderall is a central nervous system stimulant and helps to change the amounts of naturally occurring substances in the brain.
Methadone is an opioid that is sometimes used to treat severe pain in the hospital but most commonly used to treat OUD in the outpatient setting. patients with OUD usually attend a methadone clinic on a daily or weekly basis to receive their dose of methadone. 
Dangers of Combining Adderall & Methadone
Some individuals are prescribed both methadone and adderall simultaneously. This is generally safe to do particularly under the careful supervision of a doctor.
However, some Individuals may combine stimulants and opioids together in an attempt to get high. This is referred to colloquially as “Speedballing”.  If a person misuses and “speedballs” their methadone and adderall together, they may experience a number of dangerous health risks.
The main risks with overdose of methadone and other opioids is sedation and respiratory depression. The main risks of stimulant misuse are high blood pressure, tachycardia (fast heart rate), heart attack and stroke. Combining these two medications together can increase the risk of any of these adverse outcomes.
Is Mixing Adderall and Methadone Ever Safe?
Yes, potentially. There are a number of patients who may have both ADHD and may also struggle with opioid use, and thus might benefit from both medications. Generally, it is safe to combine these medications so long as the therapy is done under the supervision of a physician.
However, it is NEVER safe to combine these medications without a prescription. If you do combine these medications either with or without a prescription, you should always speak to your doctor openly and honestly so that they can counsel you appropriately about the risks, benefits, and warning signs to look out for.