Active Ingredients A to Z

Cabergoline Cabergoline is a dopamine agonist used to lower high prolactin levels and shrink prolactin-secreting pituitary tumours; long-term use, particularly at higher doses, has been linked to thickening and scarring of heart valves, so periodic heart checks are recommended. 1 medicine View → Cabergoline Calcipotriol Calcipotriol is a topical vitamin D analog for plaque and scalp psoriasis. Using more than the recommended weekly amount can push your blood calcium too high, so it must be applied only to the areas your doctor specifies. 2 medicines View → Calcipotriol Calcitriol Calcitriol is the active form of vitamin D, used for low calcium and bone disease linked to kidney failure or parathyroid problems. Because the effective dose and the harmful dose are close together, regular blood calcium monitoring is mandatory. 1 medicine View → Calcitriol Calcium Acetate Calcium acetate is a phosphate binder for high phosphate in chronic kidney disease and dialysis, not a calcium or bone supplement. It only works when taken with meals, and overuse can raise blood calcium to dangerous levels. 1 medicine View → Calcium Acetate Calcium Carbonate Calcium carbonate is an antacid and calcium supplement that neutralises stomach acid and supports bone health. Excessive intake, especially with dairy or other alkali, can cause milk-alkali syndrome, and it reduces absorption of many other drugs. 1 medicine View → Calcium Carbonate Canagliflozin Canagliflozin is an SGLT2 inhibitor for type 2 diabetes with a well-documented higher risk of lower-limb amputation. It should be paused before major surgery or fasting to avoid a serious complication called euglycemic diabetic ketoacidosis. 1 medicine View → Canagliflozin Candesartan Candesartan is an angiotensin receptor blocker that relaxes blood vessels to treat high blood pressure and heart failure. It must not be used in pregnancy: it can cause serious fetal kidney injury and death. 1 medicine View → Candesartan Capecitabine Capecitabine is an oral chemotherapy drug the body converts into fluorouracil; it commonly causes hand-foot syndrome and can cause severe, sometimes fatal, toxicity in people with a DPD enzyme deficiency, so any unexpected severe side effect needs urgent attention. 1 medicine View → Capecitabine Carbamazepine Carbamazepine is an anticonvulsant used for epilepsy, trigeminal neuralgia and bipolar disorder. It can trigger Stevens-Johnson syndrome, a severe skin reaction, so any new rash needs urgent medical review. 1 medicine View → Carbamazepine Carbidopa Carbidopa is combined with levodopa to treat Parkinson's disease, allowing more levodopa to reach the brain. Stopping it suddenly can trigger a dangerous fever-and-rigidity reaction, so it must never be withdrawn abruptly. 3 medicines View → Carbidopa Carbimazole Carbimazole is an antithyroid medicine used to treat an overactive thyroid, including Graves' disease, by slowing hormone production. Its rare but serious risk is agranulocytosis: fever, sore throat or mouth ulcers mean you must stop the drug and seek urgent medical care. 1 medicine View → Carbimazole Carvedilol Carvedilol is a beta-blocker that also relaxes blood vessels, used for high blood pressure and heart failure. It must never be stopped abruptly, since sudden withdrawal can trigger a heart attack or dangerous rebound in blood pressure. 1 medicine View → Carvedilol Cefadroxil Cefadroxil is a cephalosporin antibiotic used for skin, throat, and urinary infections. It must not be used by anyone who has had a severe allergic reaction to penicillins or other cephalosporins. 1 medicine View → Cefadroxil Cefdinir Cefdinir is a third-generation cephalosporin antibiotic used for ear, sinus, throat, and skin infections. It must not be used by anyone with a history of severe allergic reaction to penicillins or cephalosporins. 1 medicine View → Cefdinir Cefixime Cefixime is a third-generation cephalosporin antibiotic used for urinary, respiratory, and ear infections. It must not be used by anyone with a history of severe allergic reaction to penicillins or cephalosporins. 1 medicine View → Cefixime Cefpodoxime Cefpodoxime is a cephalosporin antibiotic used for respiratory, ear, skin, and urinary infections. It must not be used by anyone with a history of severe allergic reaction to penicillins or cephalosporins. 1 medicine View → Cefpodoxime Cefuroxime Cefuroxime is a cephalosporin antibiotic used for respiratory, ear, sinus, skin, and urinary infections, and early Lyme disease. It must not be used by anyone with a history of severe allergic reaction to penicillins or cephalosporins. 1 medicine View → Cefuroxime Celecoxib Celecoxib is a COX-2 selective NSAID that relieves arthritis and acute pain with less stomach irritation than older NSAIDs, but like all NSAIDs it carries a boxed warning for increased heart attack and stroke risk. 1 medicine View → Celecoxib Cephalexin Cephalexin is a first-generation cephalosporin antibiotic used for skin, throat, urinary and bone infections; people with a history of severe penicillin allergy should avoid it because of possible cross-reaction between the two antibiotic families. 2 medicines View → Cephalexin Chlorambucil Chlorambucil is an oral alkylating chemotherapy drug used mainly for chronic lymphocytic leukaemia; it suppresses the bone marrow's production of blood cells, so regular blood counts are mandatory throughout treatment. 1 medicine View → Chlorambucil Chloramphenicol Chloramphenicol is a broad-spectrum antibiotic reserved for serious infections, such as eye infections or typhoid, because systemic use carries a rare but potentially fatal risk of aplastic anaemia, a bone marrow failure to make blood cells. 1 medicine View → Chloramphenicol Chloroquine Chloroquine is an antimalarial and antirheumatic drug that can cause dangerous heart rhythm problems, especially in overdose or combined with other QT-prolonging medicines, and it must be kept well out of the reach of children. 1 medicine View → Chloroquine Chlorpromazine Chlorpromazine is a first-generation antipsychotic that can rarely cause neuroleptic malignant syndrome, a life-threatening reaction with high fever, rigid muscles and confusion that needs emergency care. 1 medicine View → Chlorpromazine Chlorthalidone Chlorthalidone is a long-acting thiazide-like diuretic used for high blood pressure and fluid retention; it can lower blood potassium and sodium, so periodic blood tests are needed, especially early in treatment. 3 medicines View → Chlorthalidone Choline Salicylate Choline salicylate is a salicylate gel applied to the mouth for ulcers and denture soreness; because it is chemically related to aspirin, it must never be used in children or teenagers due to the risk of Reye syndrome. 1 medicine View → Choline Salicylate Ciclosporin Ciclosporin is an immunosuppressant that prevents organ transplant rejection and treats severe autoimmune disease, but it can damage the kidneys: regular blood-level, kidney and blood-pressure checks are essential. 2 medicines View → Ciclosporin Cilostazol Cilostazol widens blood vessels and reduces platelet clumping to improve walking distance in intermittent claudication, but it is contraindicated in heart failure of any severity because this drug class increases the risk of death in that condition. 1 medicine View → Cilostazol Ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic reserved for infections where other antibiotics aren't suitable, because it carries boxed warnings for tendon rupture, aortic aneurysm and dissection, and nerve damage. 3 medicines View → Ciprofloxacin Citalopram Citalopram is an SSRI antidepressant that carries a dose-dependent risk of QT prolongation, an abnormal heart rhythm, so your prescriber caps the dose and keeps it lower if you are over 60 or have liver problems. 1 medicine View → Citalopram Clarithromycin Clarithromycin is a macrolide antibiotic used for respiratory, skin and stomach infections. It blocks a liver enzyme that clears certain other drugs, so combining it with colchicine, some statins, ergot medicines or pimozide can raise those drugs to dangerous, sometimes fatal, levels. 1 medicine View → Clarithromycin Clavulanate Clavulanate (clavulanic acid) protects amoxicillin from bacterial enzymes and is given only combined with it, as co-amoxiclav; its own key risk is liver injury that can appear weeks after stopping. 1 medicine View → Clavulanate Clavulanic Acid Clavulanic acid is combined with amoxicillin (co-amoxiclav) to overcome bacteria that would otherwise resist the antibiotic. The combination can cause liver injury, more often in men over 65, sometimes appearing weeks after the course ends. 1 medicine View → Clavulanic Acid Clenbuterol Clenbuterol is a long-acting beta-2 agonist used in some countries as a bronchodilator; its stimulant effect on the heart can cause dangerous fast or irregular heartbeats, and using it for weight loss or bodybuilding is not a recognised medical use and carries real cardiac risk. 1 medicine View → Clenbuterol Clindamycin Clindamycin is an antibiotic used for skin, dental, bone and some other bacterial infections. It carries a well-known risk of C. difficile colitis, so severe or persistent diarrhoea during or after treatment needs urgent medical review. 1 medicine View → Clindamycin Clobetasol Clobetasol is a very high potency topical corticosteroid for severe psoriasis, eczema and other stubborn skin conditions. Used for too long, over too large an area, or under a sealed dressing, it can suppress the body's own cortisol production and thin the skin. 1 medicine View → Clobetasol Clofazimine Clofazimine is an antileprosy antibiotic also used in some drug-resistant tuberculosis regimens. It can prolong the heart's QT interval, a risk that rises when it is combined with other QT-prolonging drugs such as bedaquiline, and it turns the skin, eyes and body fluids reddish-brown. 1 medicine View → Clofazimine Clomifene Clomifene is a fertility medicine that triggers ovulation but carries a risk of ovarian hyperstimulation and multiple pregnancy, which is why it is prescribed for only a limited number of treatment cycles. 2 medicines View → Clomifene Clomipramine Clomipramine is a tricyclic antidepressant used mainly for obsessive-compulsive disorder. An overdose is potentially fatal to the heart, and it must never be combined with, or taken within 14 days of, an MAOI antidepressant. 1 medicine View → Clomipramine Clonidine Clonidine is a central alpha-2 agonist used to lower blood pressure and to ease opioid withdrawal and ADHD symptoms. Stopping it suddenly can trigger a dangerous rebound rise in blood pressure, so it must always be tapered off gradually. 2 medicines View → Clonidine Clopidogrel Clopidogrel is an antiplatelet medicine that prevents heart attack and stroke by stopping platelets sticking together, and stopping it early after a stent can trigger a clot inside it. 1 medicine View → Clopidogrel Clotrimazole Clotrimazole is a topical antifungal for athlete's foot, ringworm, jock itch and vaginal thrush. Very little is absorbed through the skin, but an infection that does not improve or keeps coming back needs medical review rather than repeated self-treatment. 1 medicine View → Clotrimazole Colchicine Colchicine is an anti-inflammatory alkaloid used for gout flares and familial Mediterranean fever. It has a narrow safety margin, and combining it with certain antibiotics or antifungals can cause fatal toxicity. 2 medicines View → Colchicine Colestyramine Colestyramine is a bile-acid binder used to lower cholesterol and relieve itching from bile flow problems. Take other medicines and fat-soluble vitamins at least 1 hour before or 4 to 6 hours after it, or it will block their absorption. 1 medicine View → Colestyramine Conjugated Oestrogens Conjugated oestrogens are menopausal hormone therapy that relieve hot flushes and vaginal dryness, but raise the risk of blood clots, stroke and, if the uterus is intact and no progestogen is added, endometrial cancer. 1 medicine View → Conjugated Oestrogens Cyclobenzaprine Cyclobenzaprine is a short-term muscle relaxant for acute muscle spasm from injuries like back or neck strain. It must never be combined with an MAOI, a combination that can cause a fatal reaction. 1 medicine View → Cyclobenzaprine Cyclopentolate Cyclopentolate is an anticholinergic eye drop that dilates the pupil and freezes focusing for eye exams. In infants and young children it can be absorbed into the body and cause serious anticholinergic side effects. 1 medicine View → Cyclopentolate Cyclophosphamide Cyclophosphamide is a chemotherapy and immune-suppressing alkylating agent used for cancers and severe autoimmune disease. Its toxic byproduct can inflame the bladder, so high fluid intake or a protective drug is required. 1 medicine View → Cyclophosphamide Cycloserine Cycloserine is a second-line antibiotic for multidrug-resistant tuberculosis. It can cause serious central nervous system effects, including seizures, psychosis, and suicidal depression, especially at higher doses. 1 medicine View → Cycloserine Cyproheptadine Cyproheptadine is an antihistamine used for allergy symptoms and to stimulate appetite, and it can reverse serotonin syndrome. It causes marked drowsiness and should be avoided in narrow-angle glaucoma and urinary retention. 1 medicine View → Cyproheptadine Cyproterone Cyproterone blocks male hormones and is combined with an estrogen to treat severe acne, excess hair growth, and PCOS symptoms. Combined with estrogen it raises the risk of blood clots, and it must not be used in pregnancy. 2 medicines View → Cyproterone