Smooth Philtrum

Overview

The philtrum is the vertical groove that runs down the middle of the upper lip, between the base of the nose and the top of the lip. A smooth philtrum means this groove is flattened or barely defined, so the area between the nose and lip looks smooth rather than ridged.

The shape of the philtrum varies naturally from person to person, and a less-defined groove on its own is often simply a normal variation. In some contexts, however, a smooth philtrum is one of several facial features that, taken together, can point to a developmental condition. It is most often discussed as one of the characteristic facial signs linked with alcohol exposure before birth, where it appears alongside other specific features. Doctors usually grade the philtrum using a standard set of reference photographs, because describing it as simply present or absent is less reliable. On its own, a flattened groove tells us very little, and it is the combination of features, growth, development, and history that gives it meaning.

Common Causes

A smooth or flattened philtrum can arise for several reasons:

• Normal variation: Many people simply have a less-defined philtrum with no underlying condition.
• Fetal alcohol spectrum disorders: A smooth philtrum is one of the recognised facial features of fetal alcohol syndrome, usually alongside other signs.
• Certain genetic conditions: Some inherited syndromes feature subtle changes in facial structure, including the philtrum.

A flattened philtrum is meaningful mainly when it appears together with other features and a relevant history, rather than in isolation.

Associated Symptoms

When a smooth philtrum is part of a developmental condition, it often appears with other features:

• A thin upper lip
• Small eye openings
• Low birth weight and slow growth
• A small head size (microcephaly)
• Developmental delay or learning difficulties
• Behavioural and attention difficulties

Diagnosis & Evaluation

A doctor assesses the philtrum as part of a wider examination, often using a standard lip-philtrum guide to grade how flattened it is, and looks for other features and relevant history.

• Facial assessment: Comparing the philtrum and lip against reference images.
• Growth and head measurements: Tracking weight, length, and head size.
• Developmental review: Assessing milestones, learning, and behaviour.
• Specialist evaluation: For suspected developmental or genetic conditions, sometimes including genetic assessment.

Treatment & Management

A smooth philtrum itself needs no treatment; care focuses on any underlying condition and on supporting the child.

• Developmental support: Early-intervention programmes, speech and language therapy, and occupational therapy where needed.
• Educational support: Tailored help with learning and behaviour.
• Regular monitoring: Of growth, development, and wellbeing.
• Family support: Information, guidance, and connection with support services.
• Coordinated care: When several areas are affected, a team approach helps bring together medical, educational, and developmental support.

When the feature is simply a normal variation, no action is needed beyond reassurance, and the philtrum has no effect on health or function.

Self-Care & Prevention

A smooth philtrum that is simply a normal facial variation needs nothing more than reassurance. Where it is linked to alcohol exposure before birth, the key point is prevention during pregnancy:

• Avoid alcohol in pregnancy: No amount of alcohol is known to be safe at any stage of pregnancy, so avoiding it entirely is the surest way to prevent fetal alcohol spectrum disorders.
• Plan ahead: Stopping alcohol when trying to conceive helps, as the early weeks are an important time for development.
• Seek support if needed: Anyone who finds it hard to stop drinking can ask a doctor or midwife for confidential help.

For a child who has the feature as part of a condition, supportive care focuses on development, learning, and wellbeing rather than the appearance of the philtrum itself.

When to See a Doctor

See a doctor if a smooth philtrum is noticed alongside:

• Other distinctive facial features, such as a thin upper lip or small eye openings
• Slow growth, a small head size, or low birth weight
• Delayed milestones, learning difficulties, or behavioural concerns
• A history of alcohol exposure during pregnancy

Early assessment allows any underlying condition to be identified and supportive care to begin as soon as possible. A flattened philtrum alone, with normal growth and development, is usually not a cause for concern.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Fetal Alcohol Spectrum Disorders (FASDs).
2. MedlinePlus, U.S. National Library of Medicine. Fetal alcohol spectrum disorders.
3. National Institute on Alcohol Abuse and Alcoholism (NIAAA). Fetal Alcohol Spectrum Disorders.