Evening primrose oil (GLA) for skin complaints
Evening primrose oil (GLA) for skin complaints in dogs and cats: efficacy, evidence and safety.
Short & honest
Evening primrose oil contains GLA, an omega-6 fatty acid with anti-inflammatory effects. Moderate evidence (B) for atopic dermatitis in dogs, particularly as an adjunct to medication. Evidence in cats is limited.
Safety assessment: Safe when used correctly
Veterinary review not yet completed
This page is awaiting review by a registered veterinary surgeon. Until then, treat the text as education based on the sources listed — not as a verified veterinary judgement.
What is evening primrose oil?
Evening primrose oil is pressed from the seeds of Oenothera biennis and contains 8–10% gamma-linolenic acid (GLA), a polyunsaturated omega-6 fatty acid. In the body, GLA is converted to dihomo-GLA (DGLA), which produces prostaglandin E1. This substance has an anti-inflammatory effect and plays a role in the restoration of the skin barrier. In this respect, GLA differs from common omega-6 fatty acids, which can act pro-inflammatory when used excessively.
What is it used for?
The most researched area of application in dogs is atopic dermatitis — a chronic allergic skin condition accompanied by itching, red skin and recurring infections. The idea is that supplementation with GLA strengthens the skin barrier and reduces the need for anti-inflammatory medication (such as corticosteroids).
What does the research say?
Dogs
An RCT in 60 dogs with atopic dermatitis investigated the combination of borage oil (an oil with a high GLA content, similar mechanism of action) and fish oil [1]. From day 64 onwards, there was a significant steroid-sparing effect (p=0.04): dogs in the treatment group required less medication to achieve the same degree of symptom control.
An earlier crossover RCT in dogs with atopic dermatitis tested evening primrose oil combined with fish oil and showed therapeutic potential [2].
The ACVD Task Force (2001) analysed the total evidence for essential fatty acids in canine atopy and concluded that methodological consistency is lacking, but specifically pointed to the steroid-sparing studies as the most convincing indication of efficacy [3].
Important notes:
- Effects usually only appear after 6–12 weeks; stopping earlier gives an incomplete picture.
- Monotherapy is insufficient in most atopic dogs; evening primrose oil works best as a supplement to a comprehensive treatment plan.
- The positive studies generally used a combination with fish oil (omega-3), not evening primrose oil alone.
Cats
Specific evidence in cats is limited. There are no qualitatively strong RCTs available for this species. Extrapolation from dog research is possible, but not substantiated.
Safety
Evening primrose oil is generally well tolerated when used correctly. At high doses, gastrointestinal complaints may occur, including diarrhoea and greasy stools — in both dogs and cats. Long-term safety data in cats are limited.
Use in practice
| Aspect | Information |
|---|---|
| Species | Dog (reasonable evidence), cat (limited evidence) |
| Evidence verdict | B — reasonable evidence |
| Supplement to | Veterinary atopy treatment (immunotherapy, medication, elimination diet) |
| Expected response time | 6–12 weeks |
| Dosage | Determine in consultation with a veterinary surgeon |
Evening primrose oil is not a replacement for veterinary treatment of atopic dermatitis. Always use in consultation with a veterinary surgeon, especially when existing medication is being used or in cases of severe skin complaints.
Sources
[1] Saevik et al., Veterinary Dermatology 2004 — https://pubmed.ncbi.nlm.nih.gov/15214949/ [2] Sture & Lloyd, Veterinary Record 1995 — https://pubmed.ncbi.nlm.nih.gov/8553525/ [3] ACVD Task Force, Veterinary Immunology and Immunopathology 2001 — https://www.sciencedirect.com/science/article/pii/S0165242701003166
Why this verdict?
The evidence grade B is based on two RCTs in dogs with atopic dermatitis [1][2] and a narrative review by the ACVD Task Force [3]. The studies show indications of efficacy — particularly a steroid-sparing effect — but methodological quality and consistency are limited. Specific evidence in cats is almost entirely lacking.
Interactions with medication
- Combination with fish oil (omega-3) has been used in studies and appears to work synergistically; consult a veterinary surgeon regarding total fatty acid balance when using multiple oil supplements concurrently.
- When used alongside corticosteroids or other immunomodulating medication: inform the treating veterinary surgeon, given the potential steroid-sparing effect.
Legal status (Netherlands)
Evening primrose oil is freely available as a dietary supplement in the Netherlands and Belgium. There are no veterinary registration requirements for use as a supplementary supplement, but use in animals falls outside medicinal products legislation.
Sources
- [1] A randomized, controlled study to evaluate the steroid sparing effect of essential fatty acid supplementation in the treatment of canine atopic dermatitis. Veterinary Dermatology, 2004. RCT source ↗
- [2] Canine atopic disease: therapeutic use of an evening primrose oil and fish oil combination. Veterinary Record, 1995. RCT source ↗
- [3] The ACVD task force on canine atopic dermatitis (XXIII): are essential fatty acids effective?. Veterinary Immunology and Immunopathology, 2001. Narrative review source ↗
Questions about this substance for your animal?
Stuck in the information, or unsure whether a remedy is right for your animal? Send us a message. We sell nothing and give no treatment advice, but we are happy to think along — for instance in finding reliable sources or preparing your question for the vet.