Genetic factors play a big role in how people react to medications. This can make it tricky to predict who might have problems with certain drugs.

• Different Drug Processing: People’s genes can affect how their bodies handle medications. This means that some might need more or less of a drug to feel better.
• Many Genes Involved: A lot of different genes can change how strong a person's reaction to a drug is, making it hard to find a one-size-fits-all test.

Even though these challenges exist, there are some helpful solutions:

1. Pharmacogenomic Testing: This test looks at a person’s genes to find out if they might be at risk for having a bad reaction to a medicine.

2. Personalized Medicine: This approach means creating medicine plans that fit each person's genetic makeup. Doing this can help reduce the number of people who have bad reactions to drugs.

But there are still some challenges in making these solutions available to everyone. These include practical issues, like costs, as well as ethical concerns about how to use genetic information.