General Health
Medicines to Avoid With a Peanut Allergy: A UK Patient Guide
If you have a peanut allergy, it is important to know that a small number of medicines may contain ingredients derived from peanuts, including arachis oil, which is another name for peanut oil. While most medicines are suitable for people with a peanut allergy, checking any new medicine is a sensible precaution.
The patient information leaflet (PIL) can help you identify ingredients of concern, and a pharmacist can advise whether a medicine is appropriate for you. It is also important to ensure your allergy is recorded on your patient record before starting treatment.
Groundnut oil is another term that may be used for peanut-derived oil, so it is worth being familiar with all of these names.
In One Sentence:
People with a peanut allergy should avoid medicines containing arachis oil or peanut oil unless advised otherwise by a healthcare professional, and should always check the patient information leaflet and speak to a pharmacist if unsure.
Key Takeaways
What is the actual ingredient to avoid?
Arachis oil, peanut oil and groundnut oil are different names for the same peanut-derived oily carrier excipient used in some medicines.
Is it in lots of medicines?
No, only a small number of UK medicines contain arachis oil and many products have been reformulated over time.
Do I need to avoid soya too?
The peanut and soya link is largely theoretical, and routine avoidance of soya or soya lecithin is not usually recommended unless you have a known soya allergy.
How do I check a medicine?
Always read the patient information leaflet and ask a pharmacist if you are unsure about an ingredient or excipient.
What if I have a reaction?
Anaphylaxis is a medical emergency requiring immediate use of an adrenaline auto-injector if prescribed and a call to 999.
What is arachis oil, and why is it in medicines?
Arachis oil is a peanut-derived oil used as an inactive ingredient in some medicines.
Arachis oil, also known as peanut oil, groundnut oil or earthnut oil, comes from the peanut plant Arachis hypogaea. In medicines, it is generally used as an excipient rather than an active ingredient. An excipient is a substance added to help formulate a medicine, and arachis oil is often used as an inactive carrier or oily base for fat-soluble medicines and hormones.
Regulators take peanut allergy seriously because even highly purified peanut-derived ingredients may contain tiny amounts of residual protein. The former Committee on Safety of Medicines, now part of the Medicines and Healthcare products Regulatory Agency (MHRA), advises that people with a known peanut allergy should not use medicines containing arachis oil [1]. European regulatory guidance also states that purified arachis oil may still contain peanut protein and that products containing it should carry a contraindication and allergy warning [2].
This approach reflects precautionary allergen labelling regulations and the fact that peanut allergy is typically an IgE-mediated response, meaning even very small amounts of allergen can trigger symptoms in susceptible individuals.
Name on the label | What it is | Relevant if you have a peanut allergy? |
| Arachis oil | The standard pharmaceutical name for peanut oil | Yes, avoid this |
| Peanut oil, groundnut oil, earthnut oil | Other names for the same peanut oil | Yes, avoid these |
| Refined arachis oil (Arachis Oil BP) | Peanut oil processed to remove most protein | Still avoid as a precaution, though the risk is very low |
| Soya lecithin, soya, soybean oil | From soya, a legume cousin of the peanut | Usually not a concern, and only relevant if you also react to soya |
| Egg lecithin | From egg, used in some products such as propofol | Not a peanut concern |
Refined Versus Crude Peanut Oil: The Nuance That Matters
The degree of refinement plays an important role in determining potential allergy risk.
Research has found that highly refined arachis oil contains very little residual protein. In controlled challenge studies, none of the peanut-allergic subjects reacted to refined peanut oil, while some reacted to crude oil [3]. Regulatory reviews have reached similar conclusions, noting that the risk depends on how thoroughly the oil is refined [4].
However, crude unrefined peanut oil and cold-pressed peanut oil contain higher levels of peanut protein and should be avoided by people with peanut allergy. Although challenge studies suggest highly refined arachis oil presents a very low risk, UK guidance continues to recommend precautionary avoidance because there is no agreed safe protein level for every allergic individual.
"Arachis oil is the peanut ingredient that occasionally appears in a small number of medicines. The best approach is to check the leaflet for terms such as arachis, groundnut or peanut, ensure your allergy is flagged on your record and ask the pharmacist if you are unsure."
Which UK medicines can contain arachis oil?
Only a limited number of UK medicines currently contain arachis oil, and formulations can change over time.
Most medicines prescribed in the UK do not contain peanut-derived ingredients. However, some products have historically used arachis oil as an excipient. One well-known example is Sustanon, where product information states that the medicine contains arachis oil and is contraindicated in patients with peanut allergy [5].
Because manufacturers regularly review and update formulations, any list of medicines containing arachis oil should be viewed as a guide rather than an exhaustive reference. Current status can change following reformulation, so patients should always consult the latest patient information leaflet.
A key example is Naseptin. Naseptin nasal cream previously contained arachis oil, leading to concerns among patients with peanut allergy. However, the product has been reformulated and now contains medium-chain triglycerides instead. The last batches of the original peanut-oil formulation expired at the end of October 2025, meaning current supplies are arachis-oil-free [6]. Older websites and outdated web pages may still mention the previous formulation, which is why checking the current leaflet remains important.
Medicine | Type and use | Relevant ingredient | Current status for peanut allergy |
| Sustanon 250 | Testosterone injection, used for testosterone deficiency | Arachis (peanut) oil | Contraindicated. The product information says it must not be used if you are allergic to peanuts or soya |
| Cerumol ear drops | Earwax softener | Arachis (peanut) oil | Avoid. Note a separate olive oil version exists, so check which one you have |
| Colpermin | Peppermint oil capsules for irritable bowel syndrome | Arachis (peanut) oil | Avoid. It is the peppermint capsule that contains arachis oil |
| Utrogestan | Progesterone, used in HRT and fertility care | Soya lecithin and sunflower oil (no longer peanut oil) | The manufacturer advises avoiding it if you have a peanut allergy, due to the possible soya and peanut link |
| Naseptin nasal cream | Antibacterial cream for the nose | Arachis oil in the original formula only | Reformulated. The peanut-oil version left the supply chain by late 2025, so current Naseptin is peanut-oil-free |
Do I need to avoid soya and soy lecithin too?
Most people with a peanut allergy do not need to routinely avoid soya or soy lecithin in medicines.
A common peanut allergy myth is that anyone allergic to peanuts must also avoid all soya products. Peanuts and soya are both legumes, and peanut and soya proteins share some similarities, creating the possibility of cross-reactivity. However, controlled food challenges have consistently shown a low clinical reaction rate despite this theoretical link [7].
Specialists do not recommend routine soya avoidance in people with peanut allergy unless they have experienced a genuine clinical reaction to soya. This includes medicines containing soy lecithin, a commonly used emulsifier found in some inhalers and capsules. Although trace protein may be present, actual allergic reactions are uncommon.
Some manufacturers still include precautionary manufacturer notes where there is concern about potential cross-sensitivity. For example, certain medicines containing ingredients derived from Glycine max soybean may carry warnings relating to peanut allergy.
"There are plenty of soya scare stories online, but the peanut and soya link is mostly theoretical. Soya lecithin in a medicine is usually not a problem. If you have had a genuine reaction to soya, or you are unsure about a product, check with your pharmacist."
What about propofol?
Current evidence does not support routinely avoiding propofol because of peanut allergy.
Propofol is an intravenous anaesthetic that contains refined soybean oil and egg-derived ingredients, not peanut. Studies examining allergic reactions have found no link between propofol allergy and egg, soya or peanut allergy, meaning routine avoidance is not evidence-based [8].
Even so, patients should always tell their anaesthetist about any allergy before a procedure so appropriate decisions can be made.
How do I check a medicine and stay safe?
Following a simple routine can help you identify medicines that may not be suitable.
Whether you are taking a prescription medicine or an over-the-counter medicine, checking ingredients is a useful habit. Arachis oil, peanut oil, groundnut oil and earthnut oil all refer to peanut-derived ingredients. Because an excipient is not the active ingredient, it may not always trigger an automatic allergy alert within prescribing systems [9].
1. Check the leaflet and the box
The patient information leaflet lists ingredients and may include a boxed allergy warning. If you are unsure, consult the Summary of Product Characteristics (SmPC) or ask a healthcare professional.
2. Make sure your allergy is on your record
Ensure your allergy is recorded with your GP and pharmacy and appears on your NHS record. This helps healthcare professionals identify potential issues before medicines are supplied.
3. Ask your pharmacist before starting anything new
A community pharmacist can review ingredients and identify a suitable alternative if necessary. Never assume that online information reflects the current formulation of a medicine.
4. Carry your adrenaline auto-injectors
If you have been prescribed adrenaline auto-injectors such as EpiPen, Jext or Emerade, carry two devices with you and check expiry dates regularly.
"Make sure your allergy is recorded everywhere, check the leaflet of anything new and keep two in-date adrenaline pens available if prescribed. Never stop a prescribed medicine because of something you read online. Speak to your pharmacist or GP first."
Recognising a Serious Allergic Reaction
Anaphylaxis requires immediate emergency treatment.
Signs of anaphylaxis can include swelling of the throat, mouth or tongue, difficulty breathing, noisy breathing, feeling faint or dizzy and sudden collapse. Use your adrenaline auto-injector if prescribed, call 999 immediately and lie the person flat with their legs raised where possible [10].
How can Mail My Meds help?
Mail My Meds helps patients manage repeat prescriptions with confidence and peace of mind.
Repeat prescriptions, checked and delivered
Mail My Meds is a UK online pharmacy regulated by the General Pharmaceutical Council (GPhC). The service supports NHS and private repeat prescriptions, with allergy information recorded on patient profiles wherever possible. Using the Electronic Prescription Service (EPS), prescriptions can be managed and delivered directly to your home.
The pharmacy team checks orders and can help identify potential ingredient concerns. However, if you develop a new or undiagnosed allergy, it is important to inform your GP and pharmacy as soon as possible. For urgent medical concerns, contact NHS 111, and in an emergency, call 999.
Frequently Asked Questions
Can I take Utrogestan if I have a peanut allergy?
Utrogestan does not contain peanut oil, but caution is still advised.
Utrogestan contains soya lecithin and sunflower oil rather than peanut oil. However, the manufacturer advises that peanut-allergic patients should avoid it because of the possible relationship between peanut and soya allergy [11]. If Utrogestan is unsuitable, your GP may be able to discuss an alternative progesterone option.
Is highly refined peanut oil in medicines safe for allergic patients?
Evidence suggests risk is very low, but UK guidance remains precautionary.
Highly refined arachis oil contains only trace peanut protein, and challenge studies indicate a very low risk of reaction. Nevertheless, UK guidance advises avoidance as a precaution because individual sensitivity varies. Crude or cold-pressed peanut oil should always be avoided.
Does a peanut allergy mean I must avoid soya in medicines?
Routine avoidance is generally not recommended.
Peanut and soya cross-reactivity is largely theoretical and clinically uncommon. Unless you also react to soya, routine soya or soya lecithin avoidance is not recommended. Always read the leaflet and discuss any precautionary soya warning with your pharmacist.
Does Naseptin still contain peanut oil?
No, the current formulation no longer contains arachis oil.
Naseptin nasal cream previously contained arachis oil in its original formulation. It has since been reformulated to use medium-chain triglycerides, and the last peanut-oil batches expired at the end of October 2025. Always check the leaflet to confirm the current ingredients.
What should I do if I am not sure about a medicine?
Check before stopping or starting treatment.
Do not stop a prescribed medicine based solely on online information. Check the leaflet ingredients, speak to your pharmacist or GP and make sure your peanut allergy is recorded on your patient file.
Final Thoughts From Our Superintendent Pharmacist
"For most peanut-allergic patients, medicines containing arachis oil or peanut oil are uncommon, and several products have been reformulated over time, including examples such as Naseptin. Trust the current leaflet over old web pages, and remember that the peanut and soya link is mostly theoretical, with soya lecithin usually safe for most people unless they have a separate soya allergy. Keep your allergy recorded everywhere, check the leaflet of anything new, ask the pharmacist whenever you are unsure and always carry your adrenaline pens if prescribed. Most importantly, never stop a prescribed medicine without professional advice."
Sources
[1] Medicines and Healthcare products Regulatory Agency - GOV.UK
[6] Naseptin Nasal Cream - Safety Alerts - (emc) | 5524
[7] Soya-based Excipients - a Problem for People with Peanut Allergy?
[10] Allergies - NHS
[11] Utrogestan 100mg Capsules - Summary of Product Characteristics (SmPC) - (emc) | 352
About the author
Blog author
Dayna Sheppard
Dayna is a pharmacy manager with over 15 years of pharmacy experience. She is focused on delivering a safe and excellent pharmacy service for patients.
Medically reviewed by
Medical reviewer
Taslima Hussain
Taslima is a pharmacist who is passionate about patient care. She has experience working in community pharmacy as a locum.
