Pharmacy knowledge base
Health guides & medicine information
Plain-English explainers from our editorial team — what the medicines do, how the strengths differ, and how to use them safely.
Showing 133–144 of 287 guides
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Antibiotic Resistance Explained: Why Finishing the Course Matters
Summary: Antibiotic resistance happens when bacteria change so that antibiotics no longer kill them, making infections harder to treat. It is the bacteria that become resistant, not your body, so resistant infections can spread between people. Using antibiotics for viral illnesses, stopping courses early and taking leftover antibiotics all speed it up. Use them only as prescribed.
Sleep Hygiene Tips: Practical Habits for Better Rest
Summary: Good sleep hygiene means regular bed and wake times, morning daylight, limited caffeine after midday and a dark, quiet, cool bedroom. Avoid big meals and heavy drinking before bed. Wind down before sleep and keep screens out of bed. If insomnia persists for weeks despite this, see a doctor.
Managing Chronic Nerve Pain: A Practical Overview
Summary: Chronic nerve pain comes from damage to the nerves themselves, for example from diabetes, shingles or nerve compression. It feels burning, shooting or tingling. Ordinary painkillers often help less than expected, so doctors use medicines such as pregabalin that calm nerve signalling, alongside physiotherapy and psychological support. These medicines take days or weeks to work.
Modafinil vs Armodafinil: How These Wakefulness Aids Compare
Summary: Armodafinil contains one of the two mirror-image forms that make up modafinil, so the two wakefulness medicines are very closely related. They share side effects and cautions, including less reliable hormonal contraception. In the EU, modafinil is restricted to narcolepsy. Both need a prescription and a doctor's supervision.
Avanafil vs Sildenafil: How the Two ED Tablets Compare
Summary: Avanafil and sildenafil are both PDE5 inhibitors that need arousal to work; the main difference is timing. The EMA product information for Spedra advises taking avanafil about 15 to 30 minutes before sexual activity, while the Viagra product information advises sildenafil about 1 hour before. Both are short-acting, once-a-day medicines, and both are dangerous with nitrates.
Vardenafil (Levitra) Guide: What It Is and How It Works
Summary: Vardenafil, the active ingredient in Levitra, is a PDE5 inhibitor that helps erections during sexual arousal. The EMA product information for Levitra advises taking it about 25 to 60 minutes before sexual activity, and a fatty meal can delay it. It is shorter-acting than tadalafil, similar to sildenafil, and must never be combined with nitrates.
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Sildenafil Drug Interactions: Medicines and Substances to Watch
Summary: Sildenafil must never be taken with nitrate medicines or poppers, because together they can cause a dangerous drop in blood pressure. Alpha-blockers and other blood-pressure medicines need caution and supervision, and some antifungals, antibiotics, HIV medicines and grapefruit juice raise sildenafil levels. Always give your doctor or pharmacist a full list of everything you take.
Tadalafil Drug Interactions: What to Avoid and What Needs Caution
Summary: Tadalafil must never be combined with nitrate medicines or poppers, and that risk lasts much longer than with sildenafil. That is because tadalafil stays active for well over a day. Alpha-blockers and other blood-pressure medicines need caution, and some antifungals, antibiotics and HIV medicines raise tadalafil levels. Tell your doctor everything you take before starting.
ED Medication and Nitrates: Why This Combination Is Dangerous
Summary: Never combine any ED tablet, whether sildenafil, tadalafil, vardenafil or avanafil, with nitrate medicines such as GTN or isosorbide, or with poppers. Both widen blood vessels, and together they can cause blood pressure to plunge, leading to fainting, collapse or a life-threatening heart event. There is no safe dose that removes this risk.
ED Medication and Alpha-Blockers: Managing the Combination Safely
Summary: ED tablets and alpha-blockers such as tamsulosin, alfuzosin or doxazosin can often be combined, but both lower blood pressure. Together they can cause dizziness or fainting, especially when standing up. The pairing needs medical supervision, a stable alpha-blocker dose and careful ED dosing. That is very different from nitrates, which must never be combined.
Grapefruit and ED Medication: Does It Really Matter?
Summary: Grapefruit and its juice can block CYP3A4, the enzyme that breaks down sildenafil, tadalafil, vardenafil and avanafil. More of the medicine can then build up, so side effects such as headache, flushing and dizziness become more likely. It is a real but generally modest interaction, easily avoided by skipping grapefruit while you take ED medicine.
Vidalista vs Cialis: Comparing a Generic and the Original Tadalafil
Summary: Vidalista and Cialis contain the same active ingredient, tadalafil, so they work the same way and last up to 36 hours, per EMA product information. Cialis is the EU-authorised original; Vidalista is a lower-priced generic without EU authorisation. Both can be taken with or without food and are prescription-only in the EU/EEA.