Substance use disorder (SUD) is a treatable mental disorder that affects a person's brain and behavior, leading to their inability to control their use of substances like legal or illegal drugs, alcohol or medications. Individuals with substance use disorders can experience various sexual difficulties due to the impact of the substances on their physical, psychological, and interpersonal well-being. Let me tell you some causes:

1 Physical Effects - Substance abuse can lead to hormonal imbalances, reduced blood flow, and nerve damage, which can result in issues like erectile dysfunction, reduced libido, and difficulty achieving orgasm.

2 Psychological Factors - Substance use can contribute to mental health issues such as anxiety, depression, and low self-esteem, which in turn can affect sexual desire and functioning.

3 Relationship Problems - Substance abuse can strain relationships, leading to communication breakdown, lack of intimacy, and decreased sexual satisfaction.

4 Performance Anxiety - The fear of not being able to perform sexually due to the effects of substances can lead to anxiety and sexual difficulties.

5 Interference with Arousal and Sensation - Some substances can dull sensations or impair the ability to experience pleasure, making it harder to become aroused or achieve orgasm.

6 Cognitive Impairment - Drugs and alcohol can impair cognitive function, making it difficult to engage in sexual activities or make decisions about them.

7 Medication Interactions - Certain substances can interact negatively with medications prescribed for sexual difficulties, exacerbating the problem.

8 Withdrawal Effects - When individuals try to quit or cut down on substance use, they may experience withdrawal symptoms that can impact mood and sexual function.

9 Emotional Disconnect - Substance abuse can lead to emotional detachment, making it hard to connect with a partner on an emotional level, which can affect sexual intimacy.

It's important to note that the relationship between substance use disorders and sexual difficulties is complex and can vary widely based on the type of substance, the individual's overall health, and various other factors.