Medication Interactions

When you take multiple medications, they can interact with each other in ways that change how they work or cause side effects. This is why it's important to tell your doctor and pharmacist about everything you take.

Types of Interactions

Drug-Drug Interactions

One medication affects how another works. This can make medications stronger, weaker, or cause new side effects.

Drug-Food Interactions

Some foods affect medication absorption or effectiveness. Common examples include grapefruit with certain medications, and dairy with some antibiotics.

Drug-Supplement Interactions

Vitamins, minerals, and herbal supplements can interact with medications. St John's Wort, for example, affects many medications.

Common Interactions to Know

• Blood thinners (warfarin) — many interactions with food and other medications
• Grapefruit — affects cholesterol medications, some blood pressure drugs
• Antacids — can reduce absorption of other medications
• St John's Wort — affects antidepressants, contraceptives, many others
• Alcohol — interacts with many medications

Protecting Yourself

• Use one pharmacy when possible — they keep records
• Keep an updated list of all your medications
• Include over-the-counter medications and supplements
• Ask about interactions when starting new medications
• Read medication information leaflets
• Don't stop medications without medical advice

Signs of an Interaction

• New or worsening side effects
• Medication seems less effective
• Unexpected symptoms after starting something new
• Feeling unusually unwell