Penicillin 250mg tablets (phenoxymethylpenicillin) are a prescription antibiotic that may be used for acute bacterial sinusitis when symptoms have lasted around 10 days or more without improving, have become severe, or have worsened after initially getting better. It won’t help with viral sinusitis (which is the most common type), so it’s only prescribed when your symptom pattern suggests bacteria are likely involved. A pack of 40 tablets is commonly supplied to cover a 5-day course when the dose is two 250mg tablets taken four times a day, spaced evenly and taken on an empty stomach where advised. Pack size of 56 ( 2 x 28 packs supplied)
Penicillin 250mg tablets (phenoxymethylpenicillin) are a penicillin antibiotic used to treat certain bacterial infections. It’s one of those medicines that’s been around for ages, which is actually reassuring: clinicians know it well, and guidance is clear on when it helps and when it doesn’t. [1]
You’ll most often see penicillin 250mg tablets used for infections caused by bacteria that are sensitive to penicillin, including some throat and respiratory infections. For sinus symptoms, it’s only used when a clinician thinks the pattern fits acute bacterial sinusitis, rather than the much more common viral kind that clears on its own. [2]
If you’re ordering through Medical Mojo, the key thing to know is this: the right antibiotic depends on your symptoms, your medical history, and what infection is suspected. This page gives you the detail, but your online clinical assessment is what decides whether penicillin 250mg tablets are suitable for you. [1]
Antibiotic tablet for specific bacterial infections [1]
Often considered first-line for acute bacterial sinusitis in appropriate cases [2]
Needs correct timing around meals for best absorption [1]
Not suitable if you’re allergic to penicillin [1]
Additional information
Pack Size
2 x 28
MOJO WISDOM
Take control of your health by understanding your condition and what this medication is doing for you.
This deep dive explains what penicillin 250mg tablets are, who they’re for, how they work, how to take them safely, and what to watch out for. It also covers side effects, interactions, and the most common questions people ask before ordering online.
Penicillin 250mg tablets are an antibiotic used for specific bacterial infections, not colds or flu. [1]
For sinusitis, antibiotics are usually only considered when symptoms last around 10 days or more, worsen, or come back after improving. [2]
Taking penicillin 250mg tablets at the right times matters, because food can reduce absorption. [1]
The most important safety point is allergy: if you’ve ever had a serious reaction to penicillin, you must not take it. [1]
Using antibiotics only when they’re likely to help protects you and helps slow antibiotic resistance. [2]
Penicillin 250mg tablets are best thought of as a targeted tool, not a general “infection killer”. If your symptoms are viral, antibiotics won’t speed recovery and can cause side effects you didn’t need. That’s why good online services ask detailed questions before prescribing. [2]
For sinusitis specifically, most people improve without antibiotics. The people who may benefit are those whose symptoms last longer, get worse, or follow a “better then worse again” pattern. That pattern can suggest bacteria have moved in after the initial viral infection. [2]
If you do need an antibiotic, penicillin 250mg tablets are often chosen because they’re narrow-spectrum compared with some alternatives. In plain English: they can treat the likely bacteria without being overly broad. That can be a good thing for antibiotic stewardship. [2]
The other big point is how you take them. With penicillin 250mg tablets, the timing is not just a fussy detail. Taking them with meals can reduce absorption, which may reduce effectiveness. So if you’re the kind of person who forgets tablets unless they’re next to your breakfast, set an alarm instead. [1]
Finally, be honest in your consultation. Mention allergies, kidney issues, pregnancy or breastfeeding, and all medicines and supplements. It’s not “oversharing”. It’s how clinicians keep you safe. [1]
Active ingredient in penicillin 250mg tablets
The active ingredient is phenoxymethylpenicillin (also known as penicillin V). Each penicillin 250mg tablet contains phenoxymethylpenicillin, typically as phenoxymethylpenicillin potassium. [1]
The full list of excipients (non-active ingredients) varies by brand. If you have allergies or intolerances, check the patient leaflet for your specific product. [1]
What is it for? Penicillin 250mg tablets
Penicillin 250mg tablets are used to treat infections caused by bacteria that are sensitive to phenoxymethylpenicillin. Common examples include certain throat infections, sinus infections and other respiratory tract infections, depending on local guidance and individual assessment. [1]
For sinus symptoms, penicillin 250mg tablets may be prescribed for acute bacterial sinusitis when symptoms suggest bacteria are involved, particularly when symptoms last around 10 days or more without improvement, become severe, or worsen after an initial improvement. [2]
If you’re not sure whether your sinus infection is bacterial, you’re not alone. Most people can’t tell just from mucus colour or how blocked they feel. That’s why the timeline of symptoms and the overall pattern matter so much in clinical guidance. [2]
How does it work? Penicillin 250mg tablets
Penicillin 250mg tablets work by stopping bacteria from building strong cell walls. Without a stable cell wall, bacteria can’t maintain their structure and they die off. [1]
This is why penicillin 250mg tablets don’t work for viral infections. Viruses don’t have the same kind of cell wall, and antibiotics don’t stop viruses from replicating. If your symptoms are from a cold, antibiotics won’t help and can still cause side effects. [2]
In sinusitis, the idea is simple: if bacteria are driving the inflammation in the sinuses, reducing the bacterial load can help symptoms settle and reduce the risk of complications. But because many cases are viral or self-limiting, clinicians reserve antibiotics for the situations where benefit is more likely. [2]
A useful real-world way to think about it: antibiotics are not a “fast-forward button” for every infection. They’re more like the right key for the right lock. If the lock is viral, penicillin 250mg tablets are the wrong key. [2]
How to use it? Penicillin 250mg tablets
Take penicillin 250mg tablets exactly as prescribed. Try to space doses evenly across the day to keep levels steady in your body. [1]
For bacterial sinusitis, the dose for adults is, two tablets (500mg) four times daily for day days.
Take them on an empty stomach where advised, because food can reduce absorption. Many people find it easiest to take a dose first thing, then mid-morning, mid-afternoon, and before bed, but follow the schedule your prescriber gives you. [1]
Finish the course unless you’re told to stop. Stopping early can allow bacteria to recover and symptoms to return. If you develop signs of an allergic reaction, stop and seek urgent medical advice. [1]
Warnings and precautions for penicillin 250mg tablets
Do not take penicillin 250mg tablets if you are allergic to penicillin. If you’ve ever had a serious allergic reaction (like swelling of the face or throat, breathing problems, or severe rash), this is especially important. [1]
Tell your clinician if you have kidney problems, because dosing may need adjustment. Also mention any history of asthma, eczema, or hay fever, as these can be associated with a higher risk of allergy (though they don’t automatically mean you can’t take penicillin). [1]
If you’re pregnant or breastfeeding, penicillin antibiotics are commonly used when clinically needed, but the decision should still be individual. Your online consultation should cover this clearly. [1]
If you develop severe, persistent diarrhoea, especially with blood or mucus, seek medical advice. Rarely, antibiotics can be linked to serious bowel inflammation. [1]
Side effects of penicillin 250mg tablets
Many people take penicillin 250mg tablets without major issues. The most common side effects are stomach-related, such as nausea, vomiting, and diarrhoea. [1]
Some people develop thrush (oral or vaginal) because antibiotics can disrupt normal flora. If that happens, it’s treatable, but it’s worth mentioning in your follow-up. [1]
Allergic reactions can happen, and they can be serious. Seek urgent help if you get swelling of the face, lips, tongue, or throat, difficulty breathing, or a widespread rash. [1]
If you feel your symptoms are worsening rather than improving after starting treatment, check in with a clinician. It may be the wrong antibiotic for the bacteria involved, or the diagnosis may need review. [2]
Drug interactions with penicillin 250mg tablets
Always list all medicines, supplements, and herbal products in your consultation. Some interactions are clinically important and may change what’s prescribed. [1]
Methotrexate is a key example: penicillins can reduce methotrexate clearance, increasing the risk of toxicity. If you take methotrexate, you must tell your prescriber. [1]
Warfarin and other anticoagulants may be affected by antibiotics in some cases, and extra monitoring may be needed. Don’t stop any medicines yourself, but do flag them during the assessment. [1]
Some antibiotics can affect the gut flora in a way that may reduce the effectiveness of certain oral contraceptives if you have vomiting or severe diarrhoea. If that happens, follow standard contraceptive advice and speak to a clinician. [1]
FAQ about penicillin 250mg tablets
What are penicillin 250mg tablets used for?
Penicillin 250mg tablets are used for certain bacterial infections where phenoxymethylpenicillin is appropriate, based on clinical assessment. [1]
Do penicillin 250mg tablets work for sinusitis?
They may help in acute bacterial sinusitis when symptoms fit guidance, such as lasting around 10 days or more without improvement or worsening after initial improvement. [2]
Will penicillin 250mg tablets work for a cold?
No. Colds are caused by viruses, and antibiotics don’t treat viral infections. [2]
How quickly do penicillin 250mg tablets start working?
Some people feel improvement within 1 to 2 days, but it can take longer. If you’re getting worse, seek advice. [1]
Should I take penicillin 250mg tablets with food?
Often they’re taken on an empty stomach because food can reduce absorption. Follow your prescription directions. [1]
What if I miss a dose of penicillin 250mg tablets?
Take it when you remember unless it’s nearly time for your next dose. Don’t double up. [1]
Can I drink alcohol with penicillin 250mg tablets?
Alcohol doesn’t directly stop penicillin working, but it can worsen dehydration and side effects. It’s usually best to keep it minimal while unwell. [1]
What are the most common side effects of penicillin 250mg tablets?
Nausea, vomiting, diarrhoea, and thrush are among the more common side effects. [1]
Can penicillin 250mg tablets cause thrush?
Yes, antibiotics can disrupt normal flora and trigger thrush in some people. [1]
What are signs of an allergic reaction to penicillin 250mg tablets?
Swelling of the face or throat, breathing problems, widespread rash, or severe itching. Seek urgent help. [1]
Can I take penicillin 250mg tablets if I’m allergic to amoxicillin?
Amoxicillin is a penicillin. If you’ve had a true allergy, penicillin 250mg tablets may not be suitable. A clinician must assess this. [1]
Are penicillin 250mg tablets safe in pregnancy?
Penicillins are commonly used in pregnancy when needed, but your clinician should confirm suitability for you. [1]
Are penicillin 250mg tablets safe while breastfeeding?
They’re commonly used while breastfeeding when clinically needed, but discuss your situation in the consultation. [1]
Can penicillin 250mg tablets affect contraception?
Not directly, but vomiting or severe diarrhoea can reduce pill absorption. Follow standard missed-pill guidance and seek advice. [1]
Do I need antibiotics for sinusitis?
Often no. Antibiotics are usually reserved for symptoms that persist, worsen, or strongly suggest bacterial infection. [2]
Why do clinicians avoid antibiotics unless needed?
Because side effects and antibiotic resistance are real risks, and many infections improve without antibiotics. [2]
Can I stop penicillin 250mg tablets when I feel better?
Usually you should finish the prescribed course unless your clinician tells you to stop. [1]
What should I do if I get diarrhoea on penicillin 250mg tablets?
Mild diarrhoea can happen. If it’s severe, persistent, or bloody, seek medical advice. [1]
Can penicillin 250mg tablets interact with methotrexate?
Yes, it can increase methotrexate toxicity risk. Always tell your prescriber. [1]
What if my symptoms don’t improve after penicillin 250mg tablets?
Check back in. You may need reassessment, a different antibiotic, or a different diagnosis. [2]
