Side effects may include respiratory depression (decreased breathing), small pupils, sleepiness, and low blood pressure.[2] The risk of overdose is lower with buprenorphine/naloxone than with methadone.[4] However, people are more likely to stop treatment on buprenorphine/naloxone than methadone.[4] Methadone, or buprenorphine alone, are generally preferred when treatment is required during pregnancy.[4]