Certain drugs can cause small, pinpoint pupils, also known as miosis. The following drugs are known to cause constricted pupils:

• Opioids: Opioid drugs, including heroin, morphine, codeine, oxycodone, hydrocodone, and fentanyl, are notorious for causing pinpoint pupils. As these drugs bind to opioid receptors in the brain and spinal cord, they also affect the autonomic nervous system, leading to the constriction of the pupils.

• Other central nervous system depressants: Certain depressant drugs, such as benzodiazepines, barbiturates, and alcohol, can also lead to constricted pupils.

• Stimulants: While stimulants are primarily characterized by dilated pupils, high doses of certain stimulants like cocaine and amphetamines can also result in constricted pupils.

• Hypertension medications: Blood pressure medications, such as clonidine and lisinopril, are also known to cause pinpointed pupils.

It is important to note that pinpoint pupils may also occur as a result of drug interactions or polydrug use. Mixing multiple substances, especially depressants, can lead to unpredictable effects on pupil size. If you suspect that your loved one is abusing drugs, it is important to pay attention to any changes in behavior, mood swings, impaired coordination, or confusion, in addition to changes in pupil size.