Comparisons
Side by side comparisons of molecules people confuse: painkillers, sweeteners, solvents, stimulants and medicines, each one a written difference plus the two records in one table.
Caffeine vs TheobromineCaffeine carries three methyl groups and theobromine two, so caffeine blocks adenosine far harder while theobromine acts more gently and lasts longer.Caffeine vs TheophyllineTheophylline is caffeine minus one methyl group, and theophylline also relaxes airway muscle strongly enough to have been a long-standing asthma medicine.Nicotine vs CaffeineNicotine switches on acetylcholine receptors directly while caffeine blocks adenosine receptors, and nicotine is far more habit forming and clears faster.Acetaminophen vs IbuprofenIbuprofen is an NSAID that eases inflammation as well as pain, while acetaminophen acts mainly in the central nervous system and does little for inflammation.Acetaminophen vs AspirinAspirin blocks COX enzymes irreversibly and affects platelets for days, while acetaminophen works centrally and leaves inflammation and clotting alone.Aspirin vs IbuprofenAspirin and ibuprofen are both NSAIDs, but aspirin disables the COX enzyme permanently while ibuprofen lets go, so its effect fades as it clears.Ibuprofen vs NaproxenIbuprofen and naproxen are both NSAIDs, but naproxen lasts far longer, with a half-life near 14 hours against about 2 for ibuprofen.Sucralose vs AspartameSucralose is chlorinated sucrose that the body cannot digest and that survives baking, while aspartame is a dipeptide the body breaks down and heat destroys.Aspartame vs SaccharinSaccharin is the older, smaller and sweeter molecule and survives baking, while aspartame is a dipeptide that heat breaks down and that delivers phenylalanine.Xylitol vs ErythritolXylitol and erythritol are sugar alcohols one carbon apart; xylitol is about as sweet as sugar and toxic to dogs, while erythritol is less sweet and is not.Stevioside vs Rebaudioside AStevioside and rebaudioside A are steviol glycosides from the same leaf, one sugar unit apart, and rebaudioside A lacks stevioside's liquorice bitterness.Glucose vs FructoseGlucose and fructose share the formula C6H12O6, but glucose forms a six-membered ring and fructose a five-membered one, and fructose is far sweeter.Sucrose vs FructoseSucrose is table sugar, one glucose joined to one fructose, so fructose is half of it, and fructose on its own tastes sweeter gram for gram.Lactose vs GalactoseLactose is milk sugar, glucose and galactose joined together, while galactose is a single sugar, one of the two halves lactase splits lactose into.Glucose vs GlycogenGlycogen is thousands of glucose units branched together, the form in which the liver and muscles store glucose until the body needs it.Ethanol vs MethanolEthanol and methanol differ by one carbon, but the body turns methanol into formic acid, which attacks the optic nerve, and ethanol into acetic acid.Ethanol vs Isopropyl alcoholEthanol and isopropyl alcohol, or isopropanol, both disinfect, but only ethanol is a drink: the body turns isopropyl alcohol into acetone, not acetic acid.Acetone vs Isopropyl alcoholAcetone is rubbing alcohol, isopropyl alcohol, with two hydrogens removed, one oxidation step apart, and acetone is by far the harsher solvent of the two.Hydrogen peroxide vs Sodium hypochloriteHydrogen peroxide breaks down into only water and oxygen, while sodium hypochlorite, household bleach, leaves salt behind and is the stronger disinfectant.Sodium chloride vs Potassium chlorideBoth taste salty, but sodium chloride is table salt while potassium chloride, used in salt substitutes, has a metallic, faintly bitter edge.Serotonin vs DopamineDopamine is tied to motivation, reward and movement, while most of the body's serotonin is in the gut, and neither one is simply a happiness molecule.Melatonin vs SerotoninMelatonin is made from serotonin in two steps; melatonin is the body's nightfall signal, while serotonin works mostly by day and mostly in the gut.Adrenaline vs NorepinephrineAdrenaline is norepinephrine plus one methyl group; norepinephrine is released at nerve endings, adrenaline into the blood as a hormone.Estradiol vs TestosteroneEstradiol is made from testosterone by the enzyme aromatase; testosterone predominates in men and estradiol in women, and everyone makes both.Cholesterol vs TestosteroneTestosterone is built from cholesterol: cholesterol is the membrane sterol every animal cell uses, and testosterone is one of the hormones made from it.Cholecalciferol vs ErgocalciferolCholecalciferol is vitamin D3, made by human skin and found in fish, while ergocalciferol is vitamin D2 from fungi, and D3 holds blood levels better.Capsaicin vs PiperineCapsaicin from chilli and piperine from black pepper trip the same heat receptor, but capsaicin is over a hundred times hotter and its burn lingers longer.Curcumin vs PiperineCurcumin is the yellow pigment of turmeric and piperine the bite of black pepper; piperine is paired with curcumin because it helps curcumin get absorbed.Menthol vs CamphorMenthol activates the cold receptor TRPM8, while camphor works on several TRP channels including warm ones, and camphor is far more toxic if swallowed.Limonene vs LinaloolLimonene is a hydrocarbon that is the scent of citrus peel, while linalool carries an alcohol group and is the floral note in lavender.Citric acid vs Vitamin CVitamin C is ascorbic acid, a vitamin humans must get from food, while citric acid is not a vitamin at all and the body makes it constantly.Creatine vs CreatinineCreatinine is the waste product of creatine: creatine is a muscle energy reserve, and creatinine is what it breaks down into, cleared by the kidneys.Urea vs Uric acidUrea comes from breaking down amino acids and dissolves easily, while uric acid comes from purines and dissolves so poorly it can cause gout.Collagen vs GelatinGelatin is collagen that has been cooked: heat in water unwinds collagen's rigid triple helix into the loose chains that set as a gel.Starch vs CelluloseStarch and cellulose are both glucose chains, but a starch chain's alpha bonds digest and a cellulose chain's beta bonds do not, so cellulose is fibre.Diphenhydramine vs CetirizineDiphenhydramine is a first generation antihistamine that reaches the brain and causes drowsiness, while cetirizine mostly stays out and sedates far less.Loratadine vs CetirizineCetirizine reaches the brain slightly more than loratadine, acting faster but sedating a little more, while the liver turns loratadine into desloratadine.Famotidine vs OmeprazoleFamotidine turns down the histamine signal for acid and works within an hour, while omeprazole disables the acid pump itself and reduces acid more completely.Sertraline vs FluoxetineSertraline and fluoxetine are both SSRIs, but fluoxetine and its active metabolite linger for a week or more while sertraline clears in a day or two.Escitalopram vs CitalopramCitalopram is a mix of two mirror-image forms and escitalopram is the active one isolated, so half the amount does roughly the same work.Alprazolam vs DiazepamAlprazolam acts fast and clears fast, while diazepam persists far longer through active metabolites that can stretch its effect over days.Oxycodone vs HydrocodoneOxycodone and hydrocodone are nearly the same molecule, both semi-synthetic opioids made from thebaine, differing by one hydroxyl group that oxycodone carries.Amoxicillin vs AzithromycinAmoxicillin is a penicillin that blocks bacterial cell wall building, while azithromycin is a macrolide that stops protein synthesis and lingers for days.Gabapentin vs PregabalinGabapentin and pregabalin bind the same calcium channel subunit, but pregabalin is absorbed predictably and gabapentin less so as the amount rises.Atorvastatin vs RosuvastatinBoth are statins, but rosuvastatin is more potent per unit weight and is largely not cleared by CYP3A4, so it has fewer interactions than atorvastatin.Sildenafil vs TadalafilSildenafil and tadalafil are both PDE5 inhibitors, but sildenafil acts for about four to six hours while tadalafil's effect can span a day and a half.Zolpidem vs TemazepamTemazepam is a full benzodiazepine that also eases anxiety and relaxes muscle, while zolpidem is not a benzodiazepine and targets sedation more selectively.Lisinopril vs LosartanLisinopril blocks the enzyme that makes angiotensin II and losartan blocks its receptor, which is why lisinopril can cause a dry cough and losartan does not.Metformin vs SemaglutideMetformin is a tiny molecule that cuts glucose production in the liver, while semaglutide is a copy of the gut hormone GLP-1 that also curbs appetite.Sertraline vs EscitalopramBoth are SSRIs, but escitalopram is far more selective for the serotonin transporter, while sertraline also acts on the dopamine transporter.Duloxetine vs VenlafaxineDuloxetine and venlafaxine are both SNRIs, but venlafaxine acts mostly on serotonin at lower amounts while duloxetine hits both transmitters from the start.Bupropion vs SertralineSertraline is an SSRI that acts on serotonin, while bupropion acts on dopamine and norepinephrine and leaves serotonin essentially alone.Metoprolol vs PropranololPropranolol blocks beta-1 and beta-2 receptors alike and enters the brain readily, while metoprolol aims mainly at the heart's beta-1 receptors.Amlodipine vs LisinoprilAmlodipine relaxes artery walls by blocking calcium channels, while lisinopril works hormonally by cutting production of angiotensin II.Prednisone vs DexamethasoneDexamethasone is several times more potent than prednisone, lasts far longer and needs no liver activation, while prednisone holds more sodium and water.Tramadol vs OxycodoneOxycodone, sold as Oxycontin, is a plain opioid close to morphine; tramadol binds the opioid receptor weakly and also acts on serotonin and norepinephrine.Morphine vs FentanylMorphine and fentanyl bind the same opioid receptor, but synthetic fentanyl reaches the brain in minutes and acts at a small fraction of the amount.Codeine vs TramadolCodeine is a poppy alkaloid the liver turns into morphine, while tramadol is synthetic and also blocks serotonin and norepinephrine reuptake.Naloxone vs NaltrexoneNaloxone reverses an opioid overdose within minutes, while naltrexone survives the gut and lasts many hours; both block the same opioid receptor.Methylphenidate vs AmphetamineMethylphenidate blocks dopamine reuptake, while amphetamine also pushes stored dopamine out of the neuron, which is why amphetamine tends to act more strongly.Lisdexamfetamine vs DextroamphetamineLisdexamfetamine is dextroamphetamine with the amino acid lysine attached, and it does nothing until the blood cuts the lysine off.Melatonin vs ZolpidemMelatonin is a hormone that signals night has come, while zolpidem is a prescription sedative acting on the GABA-A receptor that induces sleep directly.Diazepam vs LorazepamDiazepam breaks down into several active metabolites that build up with repeated use, while lorazepam produces none, so its effect ends more cleanly.Clonazepam vs AlprazolamClonazepam lasts far longer than alprazolam, a half-life of 30 to 40 hours against about 11, so it is used for seizures and alprazolam for acute episodes.Celecoxib vs IbuprofenIbuprofen blocks COX-1 and COX-2 about equally, while celecoxib was designed to hit COX-2 and largely spare COX-1, which maintains the stomach lining.Meloxicam vs IbuprofenMeloxicam leans toward COX-2 and lingers in the body far longer than ibuprofen, and it is prescription only in most countries where ibuprofen is not.Loratadine vs DiphenhydramineDiphenhydramine, sold as Benadryl, enters the brain and causes drowsiness for a few hours, while loratadine, sold as Claritin, stays out and lasts a full day.Levocetirizine vs CetirizineCetirizine is a mix of two mirror-image forms and levocetirizine is the active one alone, so it works at about half the amount for a similar effect.Hydroxyzine vs DiphenhydramineHydroxyzine and diphenhydramine, sold as Benadryl, both cause drowsiness, but hydroxyzine lasts longer, is prescription only and also treats anxiety.Semaglutide vs TirzepatideSemaglutide acts on the GLP-1 receptor alone, while tirzepatide hits both the GIP and GLP-1 receptors, the basis for its larger reported weight loss.Finasteride vs MinoxidilFinasteride blocks the enzyme that makes DHT, the hormone behind male pattern hair loss, while minoxidil leaves hormones alone and widens scalp vessels.Isotretinoin vs TretinoinIsotretinoin and tretinoin share one formula and differ in one double bond; tretinoin is mostly used on skin and isotretinoin by mouth for severe acne.Aciclovir vs ValaciclovirValaciclovir is aciclovir with the amino acid valine attached, which the body removes, so swallowed valaciclovir delivers far more aciclovir to the blood.Amitriptyline vs NortriptylineNortriptyline is amitriptyline minus one methyl group, made from it by the body, and it is the less sedating of the two tricyclics.Quetiapine vs OlanzapineQuetiapine binds the dopamine D2 receptor loosely and is heavily sedating, while olanzapine binds more firmly and is more strongly tied to weight gain.Aripiprazole vs RisperidoneRisperidone blocks the dopamine D2 receptor outright, while aripiprazole is a partial agonist that switches it on slightly, so it raises prolactin less.Donepezil vs MemantineDonepezil makes the remaining acetylcholine last longer by blocking acetylcholinesterase, while memantine partly blocks the NMDA glutamate receptor.Sumatriptan vs NaratriptanSumatriptan acts fast and clears in about 2.5 hours, while naratriptan is slower to start and lasts longer, with a half-life near 6 hours.Hydrochlorothiazide vs FurosemideFurosemide is a strong loop diuretic acting in the loop of Henle, while hydrochlorothiazide acts further along the kidney tubule and is gentler.Losartan vs ValsartanBoth block the angiotensin II receptor, but losartan depends partly on the liver making a more active metabolite, and valsartan is active as given.Doxycycline vs AzithromycinDoxycycline and azithromycin both block bacterial protein making, but azithromycin is far larger and lingers in tissue, which is why its courses are short.Caffeine vs TheanineCaffeine is an alkaloid that blocks adenosine and produces alertness, while theanine is a tea amino acid that takes the edge off caffeine's jitteriness.Tetrahydrocannabinol vs CannabidiolTHC and CBD share one formula, but tetrahydrocannabinol closes a ring that cannabidiol leaves open, so only THC activates CB1 and intoxicates.Cannabidiol vs CannabigerolCannabigerol is the precursor the cannabis plant builds cannabidiol from, and CBG keeps an open chain where CBD has closed a ring.Taurine vs CaffeineCaffeine is the energy drink ingredient that produces alertness by blocking adenosine, while taurine is an amino sulfonic acid the body makes for other jobs.β-Carotene vs RetinolRetinol is preformed vitamin A that the body uses directly, while beta-carotene is two retinol units joined, cut into vitamin A only as the body needs it.Sodium bicarbonate vs Sodium carbonateSodium bicarbonate is baking soda, mildly alkaline and edible, while sodium carbonate is washing soda, strongly alkaline and used for laundry and grease.Acetic acid vs Citric acidAcetic acid has one acid group and is the sour and smell of vinegar, while citric acid has three, is an odourless solid and binds metal ions well.Hydrogen peroxide vs Isopropyl alcoholHydrogen peroxide kills microbes by oxidising them and breaks down to water and oxygen; isopropyl alcohol, rubbing alcohol, denatures proteins and evaporates.Ethylene glycol vs Propylene glycolThe body turns ethylene glycol into oxalic acid, which harms the kidneys, and propylene glycol into lactic acid, which it handles routinely.Glycerol vs Propylene glycolGlycerol has one more hydroxyl group than propylene glycol, making it thicker and a stronger humectant, while propylene glycol is the better flavour solvent.Xanthan gum vs Guar gumGuar gum is milled from the guar bean and thickens cold liquids cheaply, while xanthan gum is made by bacteria and holds up to heat, acid and salt.Gelatin vs PectinGelatin is an animal protein from collagen whose gel melts at body temperature, while pectin is a fruit polysaccharide that needs sugar and acid and sets firm.Agar vs GelatinAgar, or agar agar, is a seaweed polysaccharide that sets firm and melts only near 85 degrees Celsius; gelatin is an animal protein that melts near body heat.Sucralose vs SteviosideSucralose is made in a factory from sugar and stevioside is extracted from the stevia leaf, and sucralose is the sweeter of the two.Erythritol vs AlluloseErythritol is a sugar alcohol and allulose is a real sugar, so allulose browns and caramelises like sugar while erythritol does not.Monosodium glutamate vs Sodium chlorideSodium chloride tastes salty through its sodium, while monosodium glutamate tastes umami through its glutamate and carries about a third of the sodium.Lycopene vs β-CaroteneLycopene and beta-carotene share the formula C40H56, but only beta-carotene closes a ring at each end, and lycopene is red where beta-carotene is orange.Lutein vs ZeaxanthinLutein and zeaxanthin are isomers that differ in one double bond; zeaxanthin sits at the centre of the eye's macula and lutein toward its edge.Quercetin vs ResveratrolQuercetin is a flavonoid with three rings and five hydroxyl groups, common in onions and tea, while resveratrol is a simpler stilbene from grape skin.Collagen vs KeratinCollagen is a glycine-rich triple helix that strengthens skin, tendon and bone, while keratin is a cysteine-rich coil that makes hair and nail hard.Oleic acid vs Linoleic acidOleic acid has one double bond and the body can make it, while linoleic acid has two, oxidises faster and is essential, so it has to come from food.Palmitic acid vs Stearic acidStearic acid is two carbons longer than palmitic acid, so it melts at a higher temperature, and unlike palmitic acid it has little effect on blood cholesterol.Butane vs PropaneButane, C4H10, has one more carbon than propane, C3H8, and boils near freezing, so propane stays a usable gas in cold weather and butane does not.Methane vs PropaneMethane must be piped as a gas because it only liquefies near minus 162 degrees Celsius, while propane liquefies under modest pressure and can be bottled.Benzene vs TolueneToluene is benzene with a methyl group; benzene is a known human carcinogen, while toluene is not classified as one because the body can oxidise that group.Acetone vs Ethyl acetateAcetone is a fast, harsh ketone solvent, while ethyl acetate is a gentler, slower evaporating ester and is what acetone-free nail polish removers contain.Formaldehyde vs AcetaldehydeFormaldehyde is the simplest aldehyde, used in resins and embalming; acetaldehyde is what ethanol becomes in the body, long blamed for part of a hangover.Ammonia vs Sodium hypochloriteAmmonia cleans glass and grease and sodium hypochlorite is bleach, and mixing the two makes chloramines, a toxic gas that badly irritates the airways.Borax vs Sodium bicarbonateSodium bicarbonate is an edible, mildly alkaline sodium salt, while borax is a more strongly alkaline boron compound that is not edible.Dopamine vs NorepinephrineNorepinephrine is made from dopamine by adding one hydroxyl group; dopamine dominates reward and movement, norepinephrine arousal and attention.Oxytocin vs VasopressinOxytocin and vasopressin differ at only two of nine amino acids; oxytocin drives uterine contraction and milk letdown, vasopressin makes the kidney keep water.Insulin vs GlucagonInsulin lowers blood sugar by telling tissues to take glucose in and store it, while glucagon raises it by telling the liver to release stored glucose.Leptin vs GhrelinGhrelin, from the stomach, is a short term signal to eat that rises before meals, while leptin, from fat tissue, is a long term signal about energy stores.Cortisol vs AdrenalineAdrenaline acts within seconds and clears in minutes, while cortisol is a steroid hormone that works over hours on glucose, immunity and inflammation.Testosterone vs DihydrotestosteroneDihydrotestosterone is testosterone with one double bond reduced, a more potent local form made in skin, prostate and hair follicles.Estradiol vs ProgesteroneEstradiol builds the uterine lining in the first half of the menstrual cycle and progesterone maintains it in the second, after ovulation.Adenosine vs CaffeineAdenosine is the body's own sleepiness signal and caffeine blocks its receptors without switching them on, so the two are opponents rather than alternatives.Nicotinamide vs Nicotinic acidNiacin is nicotinic acid, whose acid group causes the skin flush, while niacinamide is nicotinamide, the amide form of vitamin B3, which does not flush.Maltodextrin vs StarchMaltodextrin is starch, usually corn starch, cut into short glucose chains, so it dissolves instantly and tastes faintly sweet where starch tastes of nothing.Sodium hydroxide vs Sodium bicarbonateSodium bicarbonate is a weak alkali mild enough to eat, while sodium hydroxide is caustic soda, strong enough to dissolve fat and hair and corrosive to skin.Quercetin vs Epigallocatechin gallateQuercetin is a flavonol found in onions and apples, while epigallocatechin gallate is a larger flavan-3-ol from green tea with an extra gallate ester.Armodafinil vs ModafinilModafinil is an even mix of two mirror-image forms and armodafinil is the R form alone, which clears more slowly, so its effect runs later into the day.Dexmethylphenidate vs MethylphenidateMethylphenidate is a mix of two mirror-image forms, and dexmethylphenidate is the active d-threo form isolated, so the same molecule does the work.Eszopiclone vs ZopicloneZopiclone is an even mix of two mirror-image forms, and eszopiclone is the active S form isolated, the version approved in the United States.Testosterone enanthate vs Testosterone cypionateTestosterone enanthate and testosterone cypionate differ only in the fatty tail on the same oxygen, and both release plain testosterone once inside.Fluticasone propionate vs BudesonideFluticasone propionate carries three fluorines and a sulfur and is the more potent, while budesonide has neither and also comes as a capsule for the gut.Ramipril vs LisinoprilRamipril is a prodrug the liver must convert into ramiprilat, while lisinopril is active as swallowed and leaves the body unchanged.Nifedipine vs AmlodipineAmlodipine lasts well over a day, while nifedipine clears within hours, which is why nifedipine is mostly made in slow-release forms.Diltiazem vs VerapamilDiltiazem and verapamil both act on the heart as well as blood vessels, but verapamil, a phenylalkylamine, has the stronger effect on heart rhythm.Atenolol vs PropranololPropranolol blocks beta receptors in the heart, lungs and vessels and enters the brain, while atenolol prefers the heart's receptors and barely enters it.Simvastatin vs AtorvastatinSimvastatin is made from a fungal compound and swallowed as an inactive lactone, while atorvastatin is fully synthetic and active as taken.Liraglutide vs SemaglutideLiraglutide and semaglutide both copy GLP-1, but semaglutide's longer fatty chain and one changed amino acid stretch its effect from about a day to a week.Oxazepam vs DiazepamOxazepam is one of the molecules diazepam turns into in the body, and it is cleared within hours where diazepam and nordazepam stay for days.Betamethasone vs DexamethasoneBetamethasone and dexamethasone differ only in one methyl group, which points up from the ring in one and down in the other.Tamoxifen vs LetrozoleTamoxifen blocks the estrogen receptor so estrogen cannot act, while letrozole blocks aromatase, the enzyme that makes estrogen, so less of it exists.Ropinirole vs PramipexoleRopinirole is an indolone processed by the liver, while pramipexole carries a sulfur in an aminothiazole ring and leaves largely unchanged through the kidneys.Oxcarbazepine vs CarbamazepineOxcarbazepine is carbamazepine with one added oxygen, and it does far less to speed up the liver enzymes that clear other medicines.Dutasteride vs FinasterideFinasteride blocks one form of 5-alpha reductase while dutasteride blocks both, lowering DHT further, and dutasteride stays in the body for weeks.Brexpiprazole vs AripiprazoleBrexpiprazole is the successor to aripiprazole: it switches on dopamine D2 receptors less and acts more strongly on serotonin receptors.Hyoscine butylbromide vs ScopolamineHyoscine butylbromide is scopolamine with a charged nitrogen, so it stays in the gut and relaxes its muscle, while scopolamine reaches the brain.Cortisone vs CortisolCortisone is cortisol with a ketone where cortisol has a hydroxyl group, and it does nothing at the receptor until the body turns it back into cortisol.Fluorouracil vs UracilFluorouracil is uracil with one fluorine in place of a hydrogen, a fake RNA building block that jams DNA synthesis in fast-dividing cancer cells.Adapalene vs TretinoinTretinoin is retinoic acid, the active form of vitamin A, while adapalene is a far more stable, lab-designed molecule that acts at the same receptors.Temazepam vs ZopicloneTemazepam is a benzodiazepine that also eases anxiety and relaxes muscle; zopiclone is a z-drug that targets sleep more narrowly and leaves a metallic taste.GABA vs GabapentinGabapentin is GABA with a cyclohexane ring built onto its middle carbon, which lets it reach the brain, though it never acts on the GABA receptor itself.Calcium carbonate vs Sodium bicarbonateCalcium carbonate is chalk, neutralising acid slowly and leaving calcium behind, while sodium bicarbonate is baking soda, neutralising it fast with a fizz.