A contraindication is a reason not to use a drug. It might be a condition, another medication, a pregnancy, or an age. The word appears in prescribing information and on labels, and it is not a suggestion. A contraindication means the risk of harm outweighs any potential benefit, at least in that specific situation.

Some contraindications are absolute. Giving a beta blocker to someone with severe asthma could trigger bronchospasm. Giving an ACE inhibitor during pregnancy can harm the fetus. These are hard stops. Others are relative, meaning the drug can be used with caution if the benefit justifies it. A patient with mild kidney impairment might still receive a drug that requires dose adjustment, as long as kidney function is monitored. The distinction is not always clear-cut, and clinical judgment matters.

Common categories:

• Absolute. Do not use under any circumstances.
• Relative. Use with caution, monitoring, or dose adjustment.
• Drug interactions. Combining two drugs can create a contraindication.
• Condition-specific. Liver disease, kidney disease, pregnancy, and age can all be factors.

Prescribers check contraindications before writing an order. Pharmacists check again before dispensing. The system is not perfect, but it catches many errors.