top drug - anything interactions

NSAIDs and Fluoroquinoles

together may cause seizures

Stains and Grapefruit juice

increased risk of muscle cramps / myopathy

Omeprazole and Clopidogrel

anti-platelet effects of clopidogrel are diminished

CNS drugs (SSRIs, BENZOS) and alcohol

enhanced sedation

Antacids and Tetracyclines

do not take antacids within 2-3 hours of Tetracyclines. they impair the effect

ACE inhibitors (-sartans) and potassium/potassium elevating drugs (spironolactone, trimethoprim)

ACE inhibitors increase hyperkalemia risk

First gen antihistamines and Sedative effective drugs

severe sedation bc 1gen antihistamines cause sedation

Antipsychotic Drugs and Drugs that Prolong the QT Interval (macrolides, fluoroquinolones, SSRIs)

antipsychotics prolong the QT interval as well. combined causes arrhythmia

Aspirin and Antiplatelet or Anticoagulant Drugs

low does asprin is an anti platelet.

combined effect

Opioids and Benzodiazepines

both cause respiratory depression

Beta-2 agonists and Beta-blockers

beta blockers counteract the effects of beta 2 agonists

Beta-blockers and Calcium Channel Blockers

combined cause extreme bradycardia and heart failure

Bisphosphonates and Drugs or Supplements with Multivalent Ions (zinc, magnesium, calcium, iron, and aluminum.)

reduce the effects of bisphosphonates (used for osteoporosis)

Note: multivalent ions have the same impact on fluoroquinolones, tetracyclines, and levothyroxine!

Anticonvulsant Drugs and Drugs that Lower the Seizure Threshold

Drugs that lower the seizure threshold include SSRIs, antipsychotic drugs, and tramadol. they reduce efficacy of anticonvulsants

Antimicrobial Drugs and Warfarin

antimicrobials destroy Vit K producing bacteria in the gut. warfarin is a vit k antagonist. they increase the risk of bleeding

Corticosteroids and NSAIDs

Systemic corticosteroids – such as prednisolone and hydrocortisone – increase the risk of peptic ulceration in patients taking NSAIDs.

Corticosteroids and Beta-2 Agonists / Loop-Thiazide Diuretics

Systemic corticosteroids increase the risk of low potassium levels (hypokalemia) in patients taking either beta-2 agonists (albuterol) or loop (furosemide) or thiazide diuretics (hydrochlorothiazide).

Loop Diuretics and Aminoglycosides

both classes of drugs increase kidney and ear toxity. together is enhanced

Dopaminergic Drugs and Antipsychotic Drugs

Dopaminergic drugs are used in patients with Parkinson’s disease (levodopa, pramipexole etc.). Antipsychotic drugs block dopamine receptors and so oppose the effects of dopaminergic drugs.

Macrolide Antibacterials and Statins

Macrolides (eg. clarithromycin) increase the risk of muscle-related side effects of statins.

Metformin and IV Contrast Media

IV contrast media is used for CT scans and coronary imagine. There is an increased risk of kidney damage when metformin is taken alongside IV contrast media.

Methotrexate and Penicillins

Penicillins reduce the excretion of methotrexate and so increase the risk of toxicity.

PDE5 Inhibitors and Nitrates

Both PDE5 inhibitors (sildenafil, vardenafil) and nitrates (isosorbide mononitrate) increase the risk of hypotension. This risk significantly increases if both are taken together.

Phenytoin and Estrogens / Progestogens

Phenytoin, an anticonvulsant drug, reduces both the concentration and efficacy of medicines that contain either estrogens or progestogens.

Quinine and Drugs that Prolong the QT Interval

Quinine is a drug used to treat night-time leg cramps and to treat certain types of malaria. It can prolong the QT interval, increasing the risk of arrhythmias. Therefore, it must be avoided with other drugs that also prolong the QT interval (SSRIs, macrolides, antipsychotics etc.).

Fluoroquinolones and Prednisolone

Fluoroquinolone antibacterial drugs include ciprofloxacin and levofloxacin. When taken with the corticosteroid drug prednisolone, it increases the risk of tendon rupture.

Trimethoprim and Potassium-Elevating Drugs

Drugs that elevate potassium levels include ACE inhibitors, angiotensin receptor blockers, and aldosterone antagonists. As trimethoprim, a drug used to treat UTIs, can also cause hyperkalemia, the combination of drugs must be avoided.

Immunosuppressant Drugs and Live Vaccines

can’t protect from live vax

Vancomycin and Aminoglycosides or Loop Diuretics

The risk of ototoxicity (ear damage) and nephrotoxicity (kidney damage) increases when the antibacterial drug vancomycin is taken with either an aminoglycoside antibacterial (such as gentamicin) or a loop diuretic (such as furosemide).

Z-drugs and Alcohol

Z-drugs are used in the short-term treatment of insomnia – for example: eszopiclone and zolpidem. Alcohol significantly increases the risk of CNS effects such as drowsiness and even respiratory depression.

Allopurinol and Amoxicillin

together increases the risk of skin rash

SSRI Antidepressants and Aspirin or NSAIDs

SSRI (fluoxetine, sertraline etc.) increase the risk of GI bleeding. This risk is worsened when they are taken with aspirin or NSAIDs (ibuprofen etc.).

MAO Inhibitors and Tyramine

There is a risk of hypertensive crisis if MAO inhibitors are taken with tyramine-rich foods.

5-HT3 Antagonists and Drugs that Prolong the QT Interval

5-HT3 antagonists include drugs such as ondansetron and granisetron – drugs used in the prophylaxis and treatment of nausea and vomiting. They can also prolong the QT interval and so must be avoided with other drugs that also cause this effect (SSRIs, antipsychotics, macrolides, quinine).

Levothyroxine and Insulin

Given its effect on metabolism, levothyroxine can insulin requirements in patients with diabetes mellitus.

Rifampicin and Oral Contraceptives

Rifampicin, a drug used to treat TB and leprosy, can reduce the efficacy of hormonal contraception, particularly contraception which is progestogen-only.

Metronidazole and Warfarin

Metronidazole reduces the metabolism of warfarin, increasing the risk of bleeding.

Methotrexate and Clozapine

There is a risk of dangerously low white blood cell count (neutropenia) if methotrexate and clozapine are taken at the same time.

Lithium and Loop Diuretics

Loop diuretics (eg. furosemide) can significantly increase levels of lithium, a drug used in the treatment of bipolar disorder.

Heparins and Warfarin or Antiplatelet Drugs

Heparins – whether it’s unfractionated heparin or LMWHs – increase the risk of bleeding. This risk is enhanced if heparins are taken with warfarin or other antiplatelet or anticoagulant drugs.