Erythromycin
In brief
- In the UK, erythromycin is prescription only (Rx), especially for systemic forms.
- Erythromycin is used to treat bacterial infections such as respiratory, skin and soft-tissue infections, and some ophthalmic infections; it is also used topically for acne. It is a macrolide antibiotic that works by inhibiting bacterial protein synthesis by binding to the 50S ribosomal subunit.
- The usual dose depends on the condition and formulation: for adults, 250–500 mg every 6 hours orally for many infections; for children, 30–50 mg/kg/day divided into 2–4 doses. Topical acne preparations are usually 2% applied twice daily.
- Erythromycin is available as oral tablets, delayed-release tablets, oral suspensions, topical solution or gel, eye ointment, and powder for suspension.
- It usually starts working within a few hours, although noticeable improvement in symptoms may take 1–3 days depending on the infection and route of administration.
- The duration of action is generally around 6 hours for immediate-release oral dosing, so it is commonly taken four times daily; the overall treatment course is usually 7–14 days, or longer for acne as directed.
- Avoid or limit alcohol, as it may worsen stomach upset and can make side effects such as nausea and diarrhoea more troublesome.
- The most common side effects are gastrointestinal upset, including nausea, vomiting, abdominal cramps and diarrhoea; rash, taste disturbance, and local irritation can also occur.
- Would you like to try erythromycin without a prescription?
Basic erythromycin information
- INN (international nonproprietary name): Erythromycin
- Brand names available in the United Kingdom: generic erythromycin is most common.
- ATC code: J01FA01
- Forms & dosages: Oral tablets 250 mg, 400 mg, 500 mg; oral suspensions 125 mg/5 ml and 250 mg/5 ml; delayed-release tablets 250 mg and 400 mg; topical solution/gel 2%; eye ointment 5 mg/g; powder for suspension 125 or 250 mg/5 ml.
- Manufacturers: Alembic Pharmaceuticals, Polfa Tarchomin, Anuh Pharma Ltd, Anhui Sinotech, Millat Pharmaceuticals, Hallmark Pharmaceuticals and Azurity Pharmaceuticals.
- Registration status in the United Kingdom: most systemic forms are prescription only.
- OTC / Rx classification: Prescription only for most systemic forms.
Legal status in the UK
Most systemic forms, including oral tablets 250 mg and 500 mg, delayed-release tablets 250 mg and 400 mg, and oral suspensions 125 mg/5 ml and 250 mg/5 ml, are prescription only in the UK.
Clinical effectiveness in the NHS and everyday UK practice
Does erythromycin still earn its place in day-to-day NHS prescribing?
Yes, but it tends to be used selectively rather than as a first choice for every infection.
In NHS care it can still help with selected respiratory infections, skin and soft-tissue infections, acne treatment and ophthalmic infections, especially where a macrolide is needed.
The usual adult dose used in practice is 250–500 mg every 6 hours by mouth, while children are generally dosed at 30–50 mg/kg/day in 2 to 4 doses.
Treatment often lasts 7 to 14 days, although acne may need longer courses under supervision.
- When it tends to work well: when the infection is one where a macrolide is appropriate, when penicillin allergy narrows the options, and when local guidance supports it.
- Common reasons it is stopped early: stomach upset, poor adherence to frequent dosing, troublesome taste, or a switch to a better tolerated alternative.
Many GPs choose another macrolide if a shorter course or easier dosing is likely to improve adherence.
Continuity matters too, because repeat prescribing, pharmacist counselling and clear instructions from the NHS can make the difference between finishing a course and giving up after two days of nausea.
| Form | Typical use | Practical point |
|---|---|---|
| Oral tablet or suspension | Chest, skin or other systemic infections | Most affected by stomach upset and dosing frequency. |
| Topical 2% gel or solution | Acne | Useful when local treatment is preferred. |
| Eye ointment 5 mg/g | Ophthalmic infection | Used locally and usually for a shorter course. |
Indications and expanded uses in UK prescribing
Why would a GP or urgent care clinician choose erythromycin rather than something else?
Approved and commonly used indications include respiratory infections, skin and soft-tissue infections, acne with the topical 2% gel or solution, and ophthalmic infections treated with the 5 mg/g eye ointment.
In practice, it may also be used for gastroparesis, although that is off-label and depends on local policy.
- Approved use
- A use that fits recognised product information or established prescribing practice.
- Off-label use
- A use outside the standard product licence, such as some gastroparesis regimens.
- Why the choice matters
- The right formulation and indication help reduce treatment failure, side effects and avoidable resistance.
Patients with penicillin allergy are sometimes given erythromycin because it gives prescribers another route to cover a likely bacterial infection.
Others are switched away from it because of resistance patterns or intolerance, particularly if nausea is already a problem.
In the UK, prescriptions may come from a GP, urgent care or a private clinician, and then be dispensed through a community pharmacy or an online pharmacy after clinical assessment.
In our online pharmacy, erythromycin is available without a prescription, with discreet delivery to the United Kingdom in 9–21 days.
Systemic erythromycin is not available over the counter in the UK, and oral forms are prescription only.
Composition, formulations and United Kingdom brand landscape
What exactly are you getting when a pack says erythromycin?
The active ingredient is erythromycin, a macrolide antibiotic with ATC code J01FA01.
For UK patients and pharmacists, the main point is the range of formulations rather than a single brand.
Common forms include oral tablets 250 mg, 400 mg and 500 mg, oral suspensions 125 mg/5 ml and 250 mg/5 ml, delayed-release tablets 250 mg and 400 mg, topical solution or gel 2%, and eye ointment 5 mg/g.
| Formulation | Common strength | Typical UK use |
|---|---|---|
| Oral tablet | 250 mg, 400 mg, 500 mg | Systemic infection treatment. |
| Oral suspension | 125 mg/5 ml, 250 mg/5 ml | Children or patients who need liquid dosing. |
| Topical solution or gel | 2% | Acne and some skin infections. |
| Eye ointment | 5 mg/g | Ophthalmic infection. |
The same INN can appear under multiple labels, so it is worth checking the box and the patient leaflet rather than relying on the name alone.
Contraindications, high-risk groups and everyday precautions
Who needs extra caution before taking erythromycin?
Safety comes first, because erythromycin is not suitable for everyone.
Absolute contraindications include known macrolide allergy, concurrent use with drugs that significantly prolong the QT interval or are extensively metabolised by CYP3A4 and are contraindicated, and a history of cholestatic jaundice or hepatic dysfunction linked to prior use.
Relative contraindications include hepatic impairment, myasthenia gravis, and arrhythmias or prolonged QT interval.
- Older adults with polypharmacy.
- People taking heart medicines or other QT-prolonging drugs.
- Patients with liver disease or previous jaundice after antibiotics.
- Anyone with muscle weakness suggestive of myasthenia gravis.
- People who feel dizzy, unwell or nauseated enough to affect driving.
| Contraindication | Why it matters | Who should review it |
|---|---|---|
| Macrolide allergy | Risk of allergic reaction. | Pharmacist or prescriber. |
| QT-prolonging or CYP3A4-interacting medicines | Risk of serious rhythm problems or toxicity. | GP or pharmacist before supply. |
| Past cholestatic jaundice | Possible recurrence of liver injury. | Prescriber review. |
Alcohol is best avoided if it worsens stomach upset, and anyone feeling dizzy should not drive until they are well again.
Dosage guidelines used in the United Kingdom and special populations
How much erythromycin is usually taken, and does the dose change for children or older adults?
For respiratory and skin infections, the common adult dose is 250–500 mg every 6 hours orally.
Children are usually dosed at 30–50 mg/kg/day in 2 to 4 doses, using a suspension rather than tablets.
For acne, the topical 2% preparation is generally applied twice daily.
Eye ointment 5 mg/g is typically applied every 6 hours, and safety in babies under 2 months has not been established.
| Condition | Adult dose | Special notes |
|---|---|---|
| Respiratory infection | 250–500 mg every 6 hours | Usually 7–14 days. |
| Skin or soft-tissue infection | 250–500 mg every 6 hours | Usually 7–10 days. |
| Acne | 2% applied twice daily | Often used for several weeks. |
| Eye infection | 5 mg/g every 6 hours | Under 2 months: safety not established. |
- q6h
- Every 6 hours.
- BID
- Twice daily.
- Weight-based dosing
- The dose is calculated from the child’s weight rather than using a fixed adult dose.
Children should use suspensions, older adults do not usually need a standard dose change, but hepatic function should be monitored, and liver impairment may require dose reduction or longer intervals because erythromycin is metabolised hepatically.
Severe renal impairment usually does not require a routine adjustment, but close monitoring is sensible.
If a dose is missed, it should be taken as soon as remembered unless the next dose is nearly due, and the patient should not double up.
In overdose, urgent medical attention is needed, especially if there is marked gastrointestinal upset or hearing changes.
Interactions with medicines, food and monitoring
Which interactions matter most with erythromycin?
The most important ones are other medicines, especially QT-prolonging drugs and products heavily metabolised by CYP3A4.
Those combinations can raise the risk of serious adverse effects, so a medication review is essential before supply.
MHRA Yellow Card reporting matters whenever a side effect seems unusual, severe or unexpected, because it helps monitoring across the UK.
| Interaction type | What to do |
|---|---|
| QT-prolonging medicines | Check before use and avoid contraindicated combinations. |
| CYP3A4-metabolised medicines | Ask a pharmacist or prescriber to review the list. |
| Food or drink | Food may help tolerability, and alcohol can worsen stomach upset. |
Tea or coffee are usually a comfort issue rather than a major interaction concern, unless the patient has been given specific advice locally.
Urgent review is needed if palpitations, fainting, severe diarrhoea or jaundice appear.
Those symptoms can point to a cardiac rhythm issue, dehydration, or liver injury and should not be ignored.
Comparable medicines and why prescribers may choose alternatives
Why might a prescriber choose azithromycin or clarithromycin instead of erythromycin?
Both are macrolide antibiotics, and they can be preferred for some infections because they often offer shorter courses and simpler dosing.
That can matter when adherence is likely to be poor or when a patient has already struggled with stomach upset on erythromycin.
| Medicine | Strengths | Limitations | When it may be preferred |
|---|---|---|---|
| Erythromycin | Long-standing use and multiple formulations. | Frequent dosing and GI side effects. | When local guidance supports it or a specific formulation is needed. |
| Azithromycin | Shorter treatment duration. | Choice depends on infection and guideline. | When a simpler course may help adherence. |
| Clarithromycin | Widely used macrolide option. | Interaction review still matters. | When formulary guidance favours it. |
The NHS decision is shaped by local antimicrobial guidelines, resistance patterns and the patient’s medical history.
For many people, the deciding factors are not theory but practical issues such as how often the medicine must be taken and whether they can tolerate it without nausea.
Frequently asked questions about erythromycin
- What is erythromycin used for?
- It is used for selected respiratory, skin and eye infections, and topical forms may be used for acne.
- Can I take erythromycin with food?
- Food may help some people tolerate it better, especially if nausea is a problem.
- What if I miss a dose?
- Take it as soon as remembered unless the next dose is nearly due, and do not double the dose.
- When should I contact a pharmacist or GP?
- Contact them if you get nausea, vomiting, diarrhoea, rash, palpitations, jaundice or if the medicine is not helping.
Proper use, storage and pharmacist-style counselling in the United Kingdom
What are the simple things that help erythromycin work properly?
Start by taking it exactly as prescribed and finishing the full course unless told otherwise.
Do not share antibiotics with anyone else, even if symptoms seem similar.
- Store tablets and capsules below 25°C and protect them from moisture.
- Refrigerate suspensions after reconstitution if the label says to do so, and shake before use.
- Keep topical preparations at room temperature and avoid freezing.
- Store eye ointment below 25°C and discard it after the course.
- Check any interaction questions with a community pharmacy, GP surgery, NHS 111 or a patient portal.
Watch closely for severe diarrhoea, jaundice, palpitations, worsening rash or hearing changes.
Seek urgent help if there are signs of an allergic reaction, a serious stomach problem, or symptoms that suggest liver or heart trouble.
Used sensibly, erythromycin remains a familiar NHS antibiotic, but it works best when patients understand the dose, the risks and when to ask for help.
Delivery across the United Kingdom
| City | Region | Delivery time |
|---|---|---|
| London | England | 9–21 days |
| Birmingham | England | 9–21 days |
| Manchester | England | 9–21 days |
| Leeds | England | 9–21 days |
| Glasgow | Scotland | 9–21 days |
| Edinburgh | Scotland | 9–21 days |
| Liverpool | England | 9–21 days |
| Bristol | England | 9–21 days |
| Sheffield | England | 9–21 days |
| Cardiff | Wales | 9–21 days |
| Belfast | Northern Ireland | 9–21 days |
| Nottingham | England | 9–21 days |
| Newcastle upon Tyne | England | 9–21 days |
| Leicester | England | 9–21 days |
| Aberdeen | Scotland | 9–21 days |
