Medication Interactions: 83 OTC medications That Quietly Interact with Prescription Drugs

Medication Interactions:

Medication interaction is defined as a change in the action of one medication due to the co-administration of another medicine, herb, or food or due to some underlying medical condition. Medication interactions may enhance or depress the effect of the medicines or drugs or they can produce some unexpected effect on the body.

There are a number of medication interactions that are encountered on the daily basis in the medication regimes of the patients but most important of them are the interactions that happened between prescription and OTC medications (medications that can be purchased without a prescription).

OTC medications That Quietly Interact with Prescription Drugs:

When a patient visits a doctor for any chronic condition, the doctor design a proper medication regime for that patient. However afterward, if the patient suffer from any seasonal disease for which OTC medicines are easily available, he may get it from the pharmacy without the consultation with the doctor or the pharmacist. These OTC medications, when co-administered with the prescribed medications for any chronic disease, can interact with the prescribed medication in various ways that can affect the patient’s health severely.

The most important classes of OTC medication to be considered in this regard include antacids, histamine H2 receptor antagonists, NSAIDs, cough and cold preparations and the antiasthma products.

Here are mentioned some most common OTC medications that quietly interact with the prescription drugs:

Note: Availability of medications as OTC drugs, varies from country to country. Each country has its own permitted list of OTC medications.

OTC medication	Prescription Drugs			Risk Associated with Co-administration
*Duplication of Medication*
Ibuprofen for headache (non-steroidal anti-inflammatory drugs class)	Naproxen/Diclofenac Sodium or potassium (NSAID class), also prescribed for some other condition.			Ulcer, Gastrointestinal bleeding, renal damage, increase in blood pressure.
*Medication Interactions: OTC Painkillers and Prescription Drugs*
Acetylsalicylic acid (ASA) containing pain killers	Warfarin or any other blood thinner			Increases the risk of Bleeding
	Carbonic anhydrase inhibitors (acetazolamide)			Increased plasma levels of acetazolamide
	Cytotoxics (methotrexate)			Reduced excretion of methotrexate
	Corticosteroids			Increased likelihood of stomach irritation and gastro-intestinal bleeding
	Uricosurics (sulfinpyrazone)			Reduced uricosuric effects
NSAIDs e.g. Naproxen or diclofenac etc.	Diuretics such as thiazides (e.g., Hydrochlorothiazide), loop diuretics (e.g., Furosemide), and potassium-sparing diuretics (e.g., Spironolactone) ACE inhibitors (ACEIs) such as Captopril, lisinopril, enalapril, and enalaprilat etc and Angiotensin-II receptor blockers such as losartan, valsartan, candesartan, irbesartan, Olmesartan.			NSAIDs can affect reduce the renal blood flow which affect the proper functioning of diuretics and can also decrease the effectiveness of ACEIs and ARBs. Risk of hyperkalaemia is also present. If a person needs to take anti-inflammatory medications (i.e. Ibuprofen, diclofenac or Naproxen) for a few days or a couple of weeks Then ACEI or ARB medications can be stopped for those days after proper consultation with the attending doctor and should be restarted after the patient is done taking the anti-inflammatory pills.
	Antibacterials (quinolones)			Increased risk of convulsions
	NSAIDs (including aspirin), corticosteroids, or anticoagulants			Increased likelihood of stomach irritation or bleeding (NSAIDs, anticoagulants), reduced antiplatelet effects (aspirin)
	Methotrexate			Increased toxicity
	Lithium			Reduced excretion
	Tacrolimus			Increased nephrotoxicity
Hyoscine butyl bromide	Tricyclic antidepressants (e.g. imipramine and clomipramine etc.), antipsychotics (olanzapine, clozapine etc.), antihistamines quinidine, anticholinergics (eg ipratropium, tiotropium)			Intensifies anticholinergic effect e.g. dry mouth, urinary retention, dry eyes and constipation
Paracetamol	Cholestyramine			Reduced absorption of paracetamol
	Antiemetics (metoclopramide, domperidone)			Increased rate of absorption of paracetamol
Codeine	Antidepressants, antihistamines, alcohol, antipsychotics, anxiolytics, hypnotics, concurrent opioid analgesics			Increased sedation
*Medication Interactions: OTC (Cough and Cold preparations) with Prescribed Medications*
Sedative Anti-histamines e.g. Chlorphenamine Diphenhydramine or doxylamine commonly present in cough and anti-allergy syrups.	Anti-depressants, Anxiolytics (Anti-anxiety medications), Sedatives or Opioids			Extreme sedation and drowsiness can occur as Diphenhydramine causes sedation and drowsiness as a side effect which add to the sedative effect of the Anti-depressants, Anxiolytics (Anti-anxiety medications), or other Sedatives
Diphenhydramine or doxylamine and other first generation anti-histamines also possesses anti-cholinergic effect	Antispasmodics (having anti-cholinergic effects) and anticholinergics (trihexyphenidyl, orphenadrine, urinary anticholinergics),			Dry eyes, dry mouth, urinary retention, and constipation.
Doxylamine	Monoamine Oxidase Inhibitors (MAOI) like selegiline, Rasagiline, phenelzine, tranylcypromine and isocarboxazid etc.			Increase the risk of Serotonin syndrome
Loratadine	Antibacterials (erythromycin, clarithromycin), antifungals (ketoconazole), cimetidine			Increased plasma levels of loratadine
Sympathomimetics e.g. Phenylephrine, Pseudoephedrine/ephedrine and xylometazoline (decongestants) mostly present in cough and cold medications	Monoamine Oxidase Inhibitors (MAOI) like selegiline, Rasagiline, phenelzine, tranylcypromine and isocarboxazid etc.			Hypertensive Crisis can occur. A, 14-day washout period is required between stopping an MAOI and starting pseudoephedrine.
Pseudoephedrine/ephedrine (decongestant) mostly present in cough and cold medications	Tricyclic antidepressants (imipramine, clomipramine, desipramine, amitriptyline, nortriptyline, doxepin and amoxapine etc.)			Co-administration can cause increase in blood pressure and problems in heart rhythms.
	Digitalis			Increased risk of arrhythmias
Dextromethorphan	SSRI (selective serotonin reuptake inhibitors)			Co-administration can cause serotonin syndrome, as dextromethorphan can also increase serotonin level.
*Medication Interactions: OTC Gastrointestinal Medications and Prescription drugs*
*Proton pump inhibitors*
Omeprazole & Esomeprazole (PPIs: that can inhibit liver enzyme CYP2C19).	Clopidogrel (An anti-coagulant that requires liver enzyme CYP2C19 for the conversion to its active form)			This inhibition caused by omeprazole decreases the concentration of active clopidogrel by approximately 50%, weakening its effectiveness in preventing blood clots. Esomeprazole also possesses similar effect. However, other PPIs such as lansoprazole, pantoprazole or rabeprazole. inhibit CYP2C19 to a lesser extent.
	Citalopram (An anti-depressants that is metabolised by liver enzyme CYP2C19).			QT prolongation and hyponatremia have been observed due to increase in the concentration of citalopram/Escitalopram. The maximum recommended dose for citalopram is 20mg daily when omeprazole is being co-administered. The dose shouldn’t exceed the recommended limit in order to avoid the side effect.
	Levothyroxine			Omeprazole can interfere with the absorption of oral levothyroxine by raising the gastric pH and may reduce its effectiveness. Levothyroxine works best when taken on empty stomach 30-60 min before breakfast. However, the effect of omeprazole last > 24 hours, altering the time of either medication will not avoid the drug-drug interaction. So, proper consultation is required.
	Cilostazol			Increased plasma levels of cilostazol
	Anxiolytic (Diazepam)			Enhanced effect of diazepam
	Antifungals (itraconazole, ketoconazole)			Reduced absorption of these drugs
	Voriconazole			Increased plasma levels of omeprazole and esomeprazole
*Antacids and Adsorbents*
Antacids and Adsorbents	Ketoconazole, chloroquine, penicillamine, and mycophenolate			Reduced absorption of these drugs
	Analgesics (aspirin)			Reduced serum salicylate levels and reduced absorption
	Some quinolone antibiotics (e.g. ciprofloxacin), rifampicin, tetracyclines, azithromycin, erythromycin			May interfere with absorption or peak levels
	Bisphosphonates			Reduced absorption of bisphosphonates
	Proguanil			Absorption reduced by magnesium trisilicate
	Thiazide diuretics			Increased risk of hypercalcaemia
	Tetracycline antibiotics (e.g. doxycycline)			Interferes with absorption of the antibiotic
*Anti-Helminthics*
Mebendazole	Carbamazepine, Phenytoin			Lowers plasma mebendazole
	Cimetidine			Raises plasma mebendazole
	Metronidazole			Increased risk of Stevens-Johnson syndrome
*H2-Receptor Blocker*
Ranitidine	Ketoconazole, Atazanavir			Increased absorption of these drugs
*Medication Interactions: OTC anti-Malarial medications and prescription Drugs*
Anti-Malarial (Atovaquone)	Tetracycline antibiotics (e.g. doxycycline)			Decreased plasma levels of atovaquone
	Metoclopramide			Decreased plasma levels of atovaquone
*Medication Interactions: OTC eye drops and prescription Drugs*
Chloramphenicol (topical)	Bone marrow depressants			Increased bone marrow depression
*Medication Interactions: OTC Hair and scalp medications and prescription Drugs*
Topical minoxidil	Other topical scalp medications (corticosteroids, tretinoin, dithranol)			Increased absorption of minoxidil
*Medication Interactions: OTC female specific medications and prescription Drugs*
Levonorgestrel	CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, St John’s Wort)			Reduced efficacy of levonorgestrel
Tranexamic acid	Fibrinolytics (streptokinase)			Counteracts thrombolytic effect of fibrinolytics
Ulipristal acetate	CYP3A4 inducers (e.g. rifampicin, phenytoin, carbamazepine, St John’s Wort)			Reduced efficacy of ulipristal
	Hormonal contraceptives			May reduce contraceptive action of combined hormonal and progesterone-only contraceptives
*Medication Interactions: OTC male specific medications and prescription Drugs*
Sildenafil	Nicorandil/ Nitrates (e.g. glyceryl trinitrate, isosorbide mononitrate, isosorbide dinitrate)			Increased risk of hypotension
	Alpha-blockers (e.g. alfuzosin, doxazosin, tamsulosin)			Increased risk of hypotension
	CYP3A4 inhibitors (e.g. ketoconazole, cimetidine, diltiazem, erythromycin, rifampicin, saquinavir)			Increased risk of QT interval prolongation
Tamsulosin	Antihypertensives e.g. doxazosin, indoramin, prazosin, terazosin, verapamil			Potentiates effect, resulting in dizziness and weakness
	Cimetidine, Ketoconazole			Increased plasma levels of tamsulosin
	Diclofenac, Warfarin			Increased elimination rate of tamsulosin
*Medication Interactions: OTC Anti-migraine medications and prescription Drugs*
Sumatriptan	MAOIs, ergot alkaloids			Increased risk of coronary vasospasm
	St John’s Wort			Increased serotonergic effects and Reduced plasma concentration of sumatriptan
	SSRIs			Increased risk of CNS toxicity
	Tricyclic antidepressants			Increased side-effects from tricyclic antidepressants
Prochlorperazine maleate	Lithium			Risk of severe neurotoxicity
	Alcohol, CNS depressants (e.g. tramadol, aripiprazole, chlorphenamine)			Additive CNS depressant effect
	Antihypertensives (eg ramipril, losartan, sotalol)			Increased risk of hypotension
	Alcohol			Increased risk of hypotension
*Medication interactions: Smoking cessations medication and prescription drugs*
Nicotine	Anti-arrhythmic (Adenosine)			Action potentiated
*Medication Interactions: OTC Vitamins and Supplements with prescription Drugs*
Vitamin A	Retinoids, statins			May increase blood levels of vitamin A, that may lead to chronic hypervitaminosis A
Vitamin B3 (Niacin)	Glimepiride			May increase blood sugar levels; may increase requirements for the drug
Vitamin B6	Phenobarbital, phenytoin			May reduce drug absorption and effectiveness
	Levodopa			Vitamin b6 increases the peripheral breakdown of levodopa – decreasing it’s effectiveness
Vitamin C	Aspirin			Reduced vitamin C absorption
Vitamin D	Thiazide diuretics			Increased risk of hypercalcaemia
	Antiepileptics (phenytoin)			Reduced serum vitamin D levels
Vitamin E	Aspirin			May increase risk of bleeding
Vitamin K	Anticoagulants (warfarin)			Reduced anticoagulant effects
Agnus Castus	Dopamine-receptor antagonists			May reduce effectiveness
	Dopamine-receptor agonists			Possible potentiation of effect
Calcium	Thiazide diuretics			Increased risk of hypercalcaemia
	Antibacterials (ciprofloxacin, tetracyclines, quinolones), bisphosphonates, nadolol, beta-blockers			May reduce drug absorption
Chromium	Anti-diabetic medications (insulin or sulfonylureas)			Increased risk of hypoglycaemia
	Thyroid replacement therapy			May decrease the serum level of levothyroxine.
Co-enzyme Q-10	Warfarin			May increase metabolism of the drug
	Antihypertensives			Risk of hypotension due to additive effect.
	Anti-Cancer Medications			May interfere with the action of anti-cancer medications due to antioxidant effects
Copper	Ciprofloxacin			May reduce drug absorption
Cranberry	Warfarin			May inhibit breakdown of warfarin, leading to increased warfarin activity
Echinacea	Ciclosporin			May reduce efficacy
	Methotrexate			May reduce efficacy
Feverfew	Anticoagulants, antiplatelets, NSAIDs			May increase risk of bleeding
	Antimigraine medications (e.g. ergotamine)			May increase heart rate and blood pressure because of additive vasoconstrictive effects
Fish oil/cod liver oil (EPA & DHA)	Antihypertensives			May reduce blood pressure
Fish oil/cod liver oil (EPA & DHA)	Anticoagulants, antiplatelets			May increase anti-clotting effects, leading to bleeding
Folic acid	Antiepileptics (phenobarbital, phenytoin)			May decrease levels of some antiepileptics
	Methotrexate			Reduced plasma levels of folic acid
Garlic	Anticoagulants, antiplatelets			May increase anti-clotting effects, leading to bleeding
	Antihypertensives			Risk of hypotension due to additive effect
	Isoniazid			Garlic especially in raw form may lowers the level of isoniazid
	Protease inhibitors (e.g. saquinavir)			Blood level of protease inhibitors reduced by raw garlic
	Tacrolimus			May increase the blood levels of tacrolimus, possibly enough to cause injury to the liver
Ginger	Anticoagulants (e.g. warfarin)			May increase anti-clotting effects, leading to bleeding
Glucosamine	Anticoagulants (e.g. warfarin)			Enhanced anticoagulant effect
Iodine	Antithyroid			Increased risk of hypothyroidism
Iron	Magnesium trisilicate			Reduced absorption of iron
Iron	Dopaminergics (levodopa), penicillamine, quinolone antibiotics (eg ciprofloxacin, norfloxacin, ofloxacin), zinc, bisphosphonates, levothyroxine, warfarin			Reduced absorption of these drugs
	Tetracycline antibiotics			Reduced absorption of iron and these drugs
Magnesium	Quinolone antibiotics (eg ciprofloxacin, norfloxacin, ofloxacin), tetracycline antibiotics, bisphosphonates			May decrease drug absorption
	Misoprostol			Diarrhoea
Zinc	Tetracycline antibiotics, quinolone antibiotics (ciprofloxacin, penicillamine)			Reduced absorption of these drugs
Panax Ginseng	Imatinib			May increase toxicity of drug
	Anticoagulants (e.g. warfarin)			May affect parameters of bleeding
	Antihyperglycemic medications (e.g. glipizide)			Risk of hypoglycemia
	Aspirin and other NSAIDs			Risk of bleeding
	Corticosteroids			May augment the adverse effects of corticosteroids because ginseng has its own anti-inflammatory effects. Ginseng also possesses immunostimulant effects and thus may attenuate the immunosuppressive effects of corticosteroids
	Digoxin			May increase the level of digoxin
	Estrogens			May increase the adverse effects of estrogen
	MAOIs			Risk of headache, tremors and manic episodes
	Opioids			May reduce the effectiveness of opioids
Gingko biloba	Anticoagulants			Augment the anticoagulant effect: risk of bleeding
	Antiseizure medications (e.g. phenytoin)			May reduce the efficacy of antiseizure medications due to the presence of contaminants
	Antidepressant medications			Risk of serotonin syndrome
	MAOIs (e.g. tranylcypromine)			May intensify effects of MAOIs and increase risk of adverse effects (e.g. headache, tremors, manic episodes)
	NSAIDs			Risk of bleeding increases
Green Tea	Atorvastatin Nadolol Warfarin			Green tea may lower the levels and effects of atorvastatin as well as nadolol, thus decreasing the lipid and blood pressure lowering effect of the medications respectively. Green tea may also can reduce the efficacy of warfarin, increasing risk of thromboembolism
Holy Basil	Thyroid hormones			May attenuate the efficacy of thyroid hormone drugs
	Anticoagulants and antiplatelets			May increase risk of bleeding
Licorice (Glycyrriza Glabra) True, natural licorice, not the more common, artificially flavored licorice candy.	Antihypertensives			May increase salt and water retention consequently increasing blood pressure, making antihypertensives less effective
	Chemotherapeutics			May lower the efficacy of paclitaxel and cisplatin
	Corticosteroids			May increase the adverse effects of corticosteroids
	Digoxin			May lowers the potassium level, which increases risk of digoxin toxicity
	Diuretics			May intensify the potassium-wasting effects of most diuretics and interfere with the effectiveness of potassium-sparing diuretics such as spironolactone.
	MAOIs			May intensify effects of these medications and increase risk of adverse effects (e.g., headache, tremors, manic episodes)
	Warfarin			May lower the efficacy of warfarin
Passion flower	Sedatives (e.g. benzodiazepines)			May increase sedative effect
Pelargonium	Anticoagulants (e.g. warfarin)			May increase anticoagulant effect
Potassium	ACE inhibitors, beta-blockers, ciclosporin, potassium sparing diuretics, tacrolimus, co-trimoxazole			Increased risk of hyperkalaemia
Red clover	Oestrogens			Isoflavones in red clover may increase effect of oestrogens
	Anticoagulants (e.g. Warfarin)			Coumarins in red clover may increase risk of bleeding
Valerian		Hypnotics and other sedatives	May increase sedative effect
Turmeric		Anticoagulants or blood thinners	Risk of bleeding as turmeric also possesses anticoagulant effect
Probiotics		Antibiotics	Co-administration of probiotic with antibiotic can decrease the effect of either medications depending upon the situation. So, a gap of at least 2 hours is necessary to have optimal effects of both.
Milk thistle		Insulin	Risk of hypoglycemia
Chamomile		Oral contraceptives	Decrease in the effect of oral contraceptives: as chamomile possesses estrogenic properties
		Anticoagulants or blood thinners	Risk of bleeding as chamomile also possesses blood thinning effect.
		Cyclosporine	May increase cyclosporine serum concentrations
		Barbiturates and other sedatives	May intensify or prolong effects of sedatives because its volatile oils have additive effects
		Iron supplements	May reduce iron absorption via tannins in the plant
Ashwagandha		Anti-diabetics	Risk of hypoglycemia
		Anti-hypertensive medications	Risk of hypotension
		Immunosuppressants	Interference in the function of immunosuppresants
		Sedatives	May increase sedation
Melatonin		Anticoagulants (such as warfarin)	May increase risk of bleeding
		Antiseizure medications	May lower the efficacy of antiseizure medications
		Benzodiazepines	May increase sedative effect
		Methamphetamine	May intensify the adverse effects of methamphetamine
S-adenosyl-L-methionine		Antidepressants	Risk of serotonin syndrome when given with serotonergic medications, manifested by a increase in heart rate, anxiety, gastrointestinal symptoms, severe muscle rigidity, and possible seizures
		Levodopa	May lower the efficacy of levodopa
Saw palmetto		Antiplatelets and anticoagulants (e.g., warfarin)	Risk of bleeding
		Estrogens (eg, oral contraceptives and other products)	May lower the efficacy of estrogens
Valerian		Sedatives (eg, barbiturates, benzodiazepines)	May intensify effects of sedatives
Rhodiola		Antidepressants	Risk of tachycardia
		Anticoagulants (e.g., warfarin)	May increase the blood levels of anticoagulants which raises the risk of bleeding
		Anti-inflammatory medications	Increased blood levels and possibly adverse effects
		Immunosuppressants	May decrease the efficacy of immunosuppressants
		Antidiabetic medications	Risk of hypoglycemia
		Antihypertensive medications	Risk of hypotension
Reishi		Anticoagulants and antiplatelet medications	Risk of bleeding
		Antihypertensives	Risk of hypotension
		Antihyperglycemic medications	Risk of hypoglycemia
Kava		Sedatives (e.g., barbiturates, benzodiazepines)	May increase or prolong the effects of sedatives
		Antiparkinsonian medications	May antagonize the effects of levodopa and worsen Parkinson disease May reduce metabolism of ropinirole and thus cause dopamine toxicity
		Hepatotoxic medications	May increase hepatotoxicity
Goldenseal		Antihypertensives	Berberine present in goldendeal may increase antihypertensive effects
		Antidiabetic medications	Berberine content may increase hypoglycemic effects of anti-diabetic medications
		Warfarin and heparin	May intensify the effects of warfarin and heparin, increasing risk of bleeding
Astragalus		Immunosuppressants (e.g., cyclosporine, mycophenolate, tacrolimus)	May stimulate the immune system consequently decreasing the effectiveness of immunosuppressants, especially critical after organ transplantation
		Lithium	May decrease the elimination of lithium leading to lithium toxicity.
Bacopa		Anticholinergics and the medications that can increase acetylcholine (e.g. glaucoma or Alzheimer disease medications)	May lower the efficacy of anticholinergic medications or intensify the adverse effects of cholinergic medications.
		Thyroid hormones	May increase thyroid hormone levels
		Medications metabolized by the CYP450 system (e.g. warfarin, calcium channel blockers, antiseizure medications)	May augment the risk of bleeding or lower the blood pressure with calcium channel blockers or sedation with antiseizure medications
Dehydroepiandrosterone		Anticoagulants (e.g., warfarin)	Risk of bleeding
		Antidepressants	May trigger mania
		Medications with anti-estrogenic effects (e.g. tamoxifen, anastrozole, and fulvestrant)	May lower the efficacy of anti-estrogenic medications
		Triazolam (a benzodiazepine).	May increase the sedative effect
		Bacille Calmette-Guerin (BCG) vaccine (for tuberculosis)	May decrease the effectiveness of the BCG vaccine
St. John’s wort		Benzodiazepines (eg, alprazolam, lorazepam, diazepam)	May lower the efficacy of benzodiazepines
		Cyclosporine and tacrolimus	May lowers the blood level of cyclosporine, elevating the risk of organ transplant rejection
		Digoxin	May decrease the blood level of digoxin, making it less effective leading to severe damage to the patient’s health
		Iron supplements	May decrease the absorption of iron
		MAOIs	May increase the effects of MAOIs, possibly causing tremendous increase in blood pressure requiring emergency treatment
		Ketamine	May decrease the effectiveness of ketamine
		Nonnucleoside reverse transcriptase inhibitors (e.g., nevirapine, efavirenz)	Potentiate the metabolism of these medications, reducing their efficacy
		Oral contraceptives	Increases metabolism of oral contraceptives thus reducing their efficacy
		Oxycodone, methadone, and tramadol	Decreases serum concentrations and consequently the analgesic effects of these medications
		Phenobarbital	May decrease the effectiveness of phenobarbital
		Photosensitizing medications (e.g., amiodarone, naproxen, sulphonamide antibiotics)	May increase photosensitivity
		Protease inhibitors (e.g. indinavir, saquinavir)	May reduce the efficacy of these medications by reducing their blood level.
		SSRIs (e.g. fluoxetine, paroxetine, sertraline)	May augment effects of these medications
		Statins (e.g. atorvastatin, lovastatin, rosuvastatin)	May lower the efficacy of statins
		Tricyclic antidepressants (e.g. desipramine, amitriptyline)	May intensify the effects of tricyclic antidepressants
		Warfarin and other anticoagulants (e.g., direct-acting oral anticoagulants)	May reduce blood level of warfarin and rivaroxaban, increasing risk of thromboembolism
*Medication Interactions: OTC Skin care medications and prescription Drugs*
Clotrimazole (cream)		Latex contraceptives	Reduced effectiveness of latex contraceptives
		Tacrolimus	Increased plasma levels of tacrolimus
Oral Fluconazole		Warfarin, phenytoin, theophylline, simvastatin, saquinavir, midazolam & sulphonylureas	Decreased metabolism of these drugs
		Hydrochlorothiazide, ritonavir, zidovudine	May lead to hypokalaemia
		Rifampicin, phenytoin	Increased metabolism of fluconazole
		Warfarin	Increased anticoagulant effect
*Medication Interactions: OTC weight loss medications and prescription Drugs*
Orlistat		Ciclosporin	Reduced absorption of ciclosporin
		Oral contraceptives	Decreased effect of oral contraceptives
		Fat soluble vitamins (A, D, E, K)	Decreased absorption of fat-soluble vitamins
		Antiepileptics	Increased risk of convulsions