Why does acne come back after isotretinoin? A story about diet and honesty

A consultation that began like so many others

Some time ago, during a teleconsultation, I saw a young man of about 20 who was concerned about the return of his acne.

He was an active young man, healthy-looking, with no apparent excess weight, and who seemed to take good care of his physical condition.

However, his face was once again showing inflammatory acne lesions.

He explained to me that some time earlier he had undergone treatment with isotretinoin, a medication known in Spain under brand names such as Dercutane.

During that treatment, his acne had disappeared almost completely.

He was pleased with the results and believed the problem had been definitively resolved.

But, months later, the lesions began to reappear.

—Doctor, I don't understand. I went through the treatment, the acne disappeared, and I was told it wouldn't come back. Why do I have so many breakouts again?

Her frustration was understandable.

When a person has gone through a lengthy and demanding treatment, they expect the results to last.

And that is precisely where our conversation began.

"Let's start by talking about your habits"

Before deciding on a new treatment, I wanted to get a better picture of her situation.

I asked her about her diet, whether she exercised, how she slept, and whether she had noticed any significant changes in her daily life.

—Do you eat healthily?

—Yes, doctor. I eat quite well.

—Do you eat vegetables, fruits, proteins, and fresh foods?

—Yes, of course.

—Do you exercise?

—Yes, regularly.

—Do you consume a lot of sweets, soft drinks, or processed products?

—No, doctor. I try to take care of myself.

Up to that point, the conversation seemed to describe a young man with reasonably healthy habits.

But then something unexpected happened.

A voice appeared from behind the camera.

Suddenly, I heard a voice speaking with quite a bit of energy from the back of the room.

A man appeared behind the young man.

It was his father.

—Doctor, don't believe him! He never stops eating cookies and sweets! He spends the whole day eating those things!

The young man looked surprised.

His father went on to explain that, although his son exercised and ate healthy foods, he also consumed cookies, cakes, and other sweet products very frequently.

The situation had an almost comical moment.

But behind that exchange lay an important medical lesson.

A person can genuinely believe they eat well and, at the same time, maintain habits they had not considered relevant to their condition.

It can also happen that a patient downplays certain behaviors because they are embarrassed to admit them.

The important thing is not to judge them.

The important thing is to understand what is really going on.

Part one: why can acne return after isotretinoin?

1. What is isotretinoin?

Isotretinoin is an oral retinoid used primarily for certain forms of severe acne that are resistant to other treatments or carry a significant risk of scarring.

It is one of the most effective medications available to us for treating acne.

It acts on several fundamental mechanisms of the disease:

• It considerably reduces sebum production.

• It decreases the activity and size of the sebaceous glands.

• It modifies follicular keratinization.

• It reduces the conditions that favor the proliferation of Cutibacterium acnes.

• It exerts anti-inflammatory effects.

In many patients, it makes it possible to achieve prolonged remissions.

But there is a concept that we must explain clearly.

A prolonged remission is not necessarily equivalent to a definitive cure.

2. Can acne reappear after Dercutane?

Yes.

Although isotretinoin achieves excellent results in numerous patients, some experience relapses months or years after completing treatment.

This does not necessarily mean that the medication has failed.

Nor does it prove that the previous doctor carried out an incorrect treatment.

Acne is a multifactorial disease whose course depends on age, hormonal activity, individual predisposition, initial severity, and other factors.

In certain patients, the sebaceous glands recover part of their activity after treatment.

And, if the biological conditions that favour acne persist, new lesions may appear.

3. Can it be guaranteed that acne will never return?

No.

No physician should promise all their patients that acne will disappear forever after a single cycle of isotretinoin.

The correct approach is to explain that this is a highly effective treatment, with the possibility of prolonged remissions, but also with a risk of relapse.

Expectations must be realistic.

This is especially important in young patients, because hormonal activity and skin evolution can continue changing for several years.

4. What factors can influence a relapse?

Among the factors that should be evaluated are the severity of previous acne, age, hormonal evolution, the characteristics of the treatment carried out, adherence, maintenance treatments, and individual predisposition.

It is also advisable to review modifiable factors that may contribute to worsening, including diet in certain patients.

However, not all relapses have an identifiable cause and should not be automatically attributed to diet.

Second part: the relationship between diet and acne

5. Acne is not simply a disease of oily skin

For a long time, acne was explained primarily as a problem of excess sebum and clogged pores.

Today we know that it is far more complex.

Four fundamental mechanisms are involved:

• Sebum production and composition.

• Abnormalities in the keratinization of the pilosebaceous follicle.

• Activity of Cutibacterium acnes and its interaction with the skin environment.

• Inflammatory and immune response.

To these mechanisms are added hormonal, genetic, and environmental influences.

Diet can interact with some of these pathways.

But that does not mean that all patients have acne because of poor eating habits.

6. What is the relationship between sugar and acne?

Research has paid particular attention to high glycemic index foods and diets with a high glycemic load.

These dietary patterns can promote rises in glucose and insulin after meals.

Insulin is involved in metabolic mechanisms that can also influence the activity of the sebaceous glands and certain cell growth pathways.

In some patients, a diet with a high glycemic load may contribute to worsening acne.

Available clinical trials suggest that reducing glycemic load can improve lesions in certain groups.

However, the studies are relatively small and not all of them show identical results.

Therefore, diet is a potentially relevant modifiable factor, not a universal explanation for all cases of acne.

7. What are the glycemic index and glycemic load?

The glycemic index describes how quickly a carbohydrate-containing food raises blood glucose, under standardized conditions.

The glycemic load also incorporates the amount of carbohydrates in a serving.

This difference is important.

It is not enough to classify a food as good or bad based on its glycemic index.

The amount consumed and the composition of the meal also influence the metabolic response.

A diet based primarily on refined and sugary products can produce a different glycemic exposure than one rich in legumes, vegetables, whole grains, and minimally processed foods.

8. Insulin, IGF-1, and Sebaceous Glands

Insulin and insulin-like growth factor 1, known as IGF-1, are involved in mechanisms of growth, metabolism, and cell signaling.

In acne research, their relationship with the following has been studied:

• Sebum production.

• Sebocyte activity.

• Keratinocyte proliferation.

• Androgenic signaling.

• Certain inflammatory pathways.

These mechanisms help explain why the metabolic environment may influence the disease.

However, they do not allow us to diagnose the cause of a person's acne solely by observing what they eat.

9. What role does mTORC1 play?

mTORC1 is a cell signaling complex that responds to signals related to nutrients, energy, and growth factors.

It is involved in cell synthesis and growth processes.

Its possible involvement in acne has been investigated due to its relationship with sebaceous activity and other cellular responses.

Insulin, IGF-1, and certain nutrients may interact with pathways that regulate mTORC1.

However, it would be incorrect to reduce the entire pathophysiology of acne to a single molecular pathway.

Acne is a complex disease, not simply a consequence of having elevated insulin.

10. Can store-bought cookies make acne worse?

In certain patients, high and frequent consumption of products rich in added sugars and refined carbohydrates can contribute to the worsening of acne.

Many cookies, cakes, and pastries share these characteristics.

But we must be precise.

Not all cookies have the same composition.

And there is no clinical test that allows us to state that eating a specific cookie will produce an acne lesion the following day.

The problem that deserves study is the habitual dietary pattern, not the demonization of an isolated food.

11. Do ultra-processed foods cause acne?

The term ultra-processed describes a broad category of food products.

Not all of them have the same nutritional composition, nor do they necessarily produce the same physiological effects.

Some contain significant amounts of refined sugars and have a high energy density.

Others have different profiles.

The research on diet and acne is more consistent with regard to certain glycemic load patterns than with asserting that all ultra-processed foods cause acne simply by virtue of belonging to that category.

For this reason, it is worth analyzing what the patient actually eats, rather than using a food label as a diagnosis.

12. What about vegetable oils?

There is not enough clinical evidence to state that all vegetable oils cause acne.

Olive oil, sunflower oil, and other plant-based sources have different compositions.

It is also incorrect to attribute a patient's acne to a specific ingredient without a proper evaluation.

The overall quality of the diet matters more than a simplified explanation based on a single component.

13. Do sweeteners and chemical additives cause acne?

We currently do not have robust clinical evidence to support the claim that authorized sweeteners or food additives, considered in general terms, are direct causes of acne.

It is important to distinguish between biological hypotheses, experimental findings, and clinical evidence in human beings.

A suspected association should not be presented as demonstrated causality.

14. What about milk and dairy products?

Some observational studies have found associations between milk consumption, especially in certain populations, and the presence of acne.

Mechanisms related to IGF-1 and other hormonal signals have been proposed.

However, the evidence is heterogeneous and may be influenced by confounding factors.

This does not mean that all people with acne should eliminate dairy from their diet.

A dietary restriction should have a reasonable justification and avoid nutritional deficiencies.

15. Can protein powders have an influence?

In some patients, a relationship has been suspected between certain whey protein supplements and the worsening of acne.

The evidence is limited and does not demonstrate that all protein supplements cause lesions.

But it is a piece of information that may deserve attention when a young patient plays sports and regularly consumes supplements.

Part three: why can a slim, athletic young person have acne?

16. Being slim does not necessarily mean having a balanced diet

This was one of the aspects that struck me the most during that consultation.

The young man had a healthy physical appearance.

He played sports and did not present obvious excess weight.

But that does not make it possible to know their complete diet.

A person can eat vegetables, fruits, and proteins, and also consume sugary products many times a day.

Both situations can coexist.

Body weight alone does not reflect the nutritional quality of a diet.

17. Physical exercise does not automatically compensate for all dietary habits

Physical activity has numerous metabolic, cardiovascular, and psychological benefits.

But practicing sport does not automatically turn any eating pattern into a healthy one.

Nor does it offer absolute protection against acne.

Genetics, age, hormones, and skin inflammation continue to play an important role.

18. Can you have acne with normal metabolic test results?

Yes.

A person can have glucose and insulin within normal ranges and still present with acne.

The skin mechanisms related to hormones and growth factors do not necessarily involve a detectable metabolic disease.

Insulin resistance tests should not be requested indiscriminately for all patients with acne.

The need for additional studies depends on the symptoms and clinical findings.

My hormones are normal… so why do I have acne and hair loss?

Part four: honesty in the medical consultation

19. Why do some patients not tell the whole truth?

There is not always a conscious intention to deceive.

Sometimes, the patient:

• Does not consider a habit relevant.

• Forgets details of their routine.

• Has an incomplete perception of what they consume.

• Feels embarrassed.

• They are afraid of being reprimanded.

• They want to present a positive image of themselves.

In adolescents and young adults, the presence of family members can also change the way they respond.

That is why it is important for the consultation to allow for calm and confidential conversation.

20. The difference between asking 'do you eat healthily?' and understanding what someone actually eats

If we ask a patient whether they eat healthily, the answer depends on their own interpretation.

For one person, eating healthily means not drinking alcohol.

For another, it means doing sport.

For another, it means having fruit every morning.

But none of these answers fully describes their diet.

Sometimes, it is more useful to reconstruct a typical day:

• What did you have for breakfast yesterday?

• What did you eat mid-morning?

• What did you have after lunch?

• What do you usually eat when you are studying or sitting in front of the computer?

• How many times a week do you have sweets or soft drinks?

These questions provide much more concrete information.

21. Can lying to your doctor harm the diagnosis?

Yes. Deliberately concealing important information can make clinical assessment and treatment selection more difficult.

But the doctor also has a responsibility to ask clear questions and to build a relationship that encourages honest answers.

The consultation should not turn into an interrogation or a search for someone to blame.

Honesty is useful when trust exists. And trust requires the absence of judgment.

22. The patient should not be afraid to acknowledge their habits

A doctor does not need to hear that their patient leads a perfect life.

You need to know the reality.

If you consume sweets daily, you can say so.

If you have stopped a treatment before completing it, the same applies.

If you smoke, vape, use supplements, or do not follow a regimen correctly, it is important to mention it.

The goal is not to reprimand.

It is to understand the factors that can affect the condition and avoid decisions based on incomplete information.

23. What happens when a family member intervenes during a teleconsultation?

The intervention of a family member can provide useful information, but it also raises questions of confidentiality and autonomy.

In the case of an adult patient, their participation and the presence of third parties must respect their consent.

The physician must listen, but also ensure that the patient is able to speak freely.

A family member's input does not automatically turn a statement into a demonstrated clinical fact.

Information must be integrated into the assessment without replacing the patient's voice.

Part Five: how to address an acne relapse

24. First, confirm what type of acne has reappeared

Not all lesions that look like acne have the same origin.

The evaluation should consider:

• Comedones.

• Inflammatory papules.

• Pustules.

• Nodules.

• Facial or body distribution.

• Severity.

• Risk of scarring.

• Possible alternative diagnoses.

In teleconsultation, the quality of images and the available examination may limit diagnostic accuracy.

25. Reviewing previous isotretinoin treatment

It is important to know:

• When the treatment began.

• How long it lasted.

• What dose was used.

• Whether there were any interruptions.

• How the lesions evolved.

• When the relapse appeared.

• Whether maintenance treatment was carried out.

The decision to repeat isotretinoin should not be made automatically simply because the acne has returned.

The current severity, alternatives, risks, and necessary follow-up must all be assessed.

26. Is it always necessary to repeat Dercutane?

No.

Some relapses can be managed with appropriate topical treatments.

Others may require systemic treatment.

In certain situations, a new course of isotretinoin may be indicated.

The choice depends on individual assessment.

Isotretinoin requires a prescription and medical supervision, as well as the corresponding safety measures.

27. What role does maintenance treatment play?

After controlling acne, some patients may benefit from maintenance treatment — for example, with topical retinoids when indicated and tolerated.

The strategy must be individualised.

The goal is to reduce the appearance of new lesions and protect the skin from scarring.

TCA CROSS for acne scars at Clínica Valorian

28. How can diet be improved without falling into extreme restrictions?

I do not recommend turning diet into an endless list of forbidden foods.

A reasonable strategy involves identifying habits that can be modified in a sustainable way.

For example:

• Reducing the regular consumption of sugary drinks and high-glycaemic-load sweet products.

• Prioritising minimally processed foods that are rich in fibre.

• Maintaining an adequate protein intake.

• Choosing carbohydrate sources in line with individual needs.

• Avoiding unjustified restrictions that may harm nutrition or one's relationship with food.

It is not necessary to promise that eliminating sugar will make all acne disappear.

The goal is to improve a potentially modifiable factor within a comprehensive medical treatment.

29. How long does it take to evaluate a dietary change?

Acne progression is measured in weeks, not hours.

Dietary changes should be assessed over a sufficient period of time, keeping the rest of the treatment stable and avoiding modifying too many variables simultaneously when trying to interpret the response.

In clinical studies, dietary interventions are typically evaluated over several weeks.

It makes no sense to conclude that a food causes acne because a pimple appears immediately after consuming it.

30. Should the patient feel guilty for having acne?

No.

Acne has a multifactorial biological basis.

It can affect people with excellent habits.

Acknowledging that diet may play a role in some cases does not mean holding the patient morally responsible for their condition.

The purpose of reviewing habits is to find opportunities for improvement, not to assign blame.

Sixth part: frequently asked questions

31. Is it normal for acne to return a year after isotretinoin?

It can happen. Isotretinoin is very effective, but some patients experience relapses months or years after completing it.

32. Does a relapse mean the first treatment was done incorrectly?

Not necessarily. The previous regimen and the course of the condition need to be reviewed, but a relapse can occur even after a correctly administered treatment.

33. Can eating cookies every day make acne worse?

Frequent consumption of high glycemic load foods can contribute to worsening acne in certain individuals. It does not, on its own, establish the cause of a relapse.

34. Does giving up sugar cure acne?

There is no evidence that eliminating sugar cures all cases. A lower glycemic load diet may help some patients, but it does not replace medical treatment when that is indicated.

35. Is acne an inflammatory disease?

Yes. Inflammation is part of its pathophysiology, along with sebum production, follicular keratinization, and other mechanisms.

36. Can I have acne even if I exercise a lot?

Yes. Physical activity provides important benefits, but it does not eliminate the predisposition to acne.

37. Does having acne mean I have insulin resistance?

No. Having acne does not allow a diagnosis of insulin resistance to be made. Metabolic studies should be requested when there is a clinical indication.

38. Do ultra-processed products cause acne?

Some dietary patterns rich in refined and sugary products may be associated with greater acne activity. It has not been proven that all ultra-processed products have the same effect.

39. Do vegetable oils cause acne?

There is insufficient evidence to claim that all vegetable oils cause acne. It is important to assess the overall diet as a whole.

40. Can dairy products have an influence?

Some observational studies find associations, especially with certain types of milk, but the relationship is not consistent and does not justify general restrictions for all patients.

41. What should I do if acne comes back after Dercutane?

Seek a medical evaluation to determine the severity, review the previous treatment, and decide whether a topical treatment is sufficient or whether a different approach is needed.

42. Should I tell my doctor that I eat sweets every day?

Yes. It is potentially useful information, just like medications, supplements, sleep habits, and other aspects of daily life.

A final reflection: your doctor needs to know your real life

That teleconsultation began with a familiar question:

"Doctor, why has my acne come back?"

But it ended up reminding me of something I consider essential.

Medicine is not only about prescribing medications.

It is about listening, observing, asking questions, and understanding.

The young man had completed an effective treatment.

His acne had improved.

And then it had come back.

His father's intervention made it possible to uncover a dietary habit that had not initially come up in our conversation.

Does that mean the biscuits were the sole cause of his acne?

We cannot say that with certainty.

But it does mean that we now had additional information to carry out a more complete assessment.

And that can change the way treatment is approached.

To my patients I would say something very simple:

Do not try to present a perfect life to your doctor.

If you eat sweets, say so.

If you are not following a treatment correctly, explain it.

If you have doubts, fears, or habits that are hard to admit, talk about them.

And we as doctors must also remember that it is our responsibility to listen without judging.

Because a good clinical history does not arise solely from asking questions.

It arises from trust.