Herpes vs. syphilis (primary stage)

Here we’ll show you the differences between herpes and syphilis skin lesions, which look similar and are easily confused.

It’s important to distinguish between these two conditions:

Unlike herpes, syphilis may be easily cured if treated in time.
Unlike herpes, syphilis can have devastating health effects if it’s not treated.

As in other chapters, here we present tables with important facts, followed by frequently asked questions answered by an expert STD doctor.

Table 1. Similarities of and differences between these conditions’ common symptoms (what the patient feels)

In the table below, we summarize the common symptoms (what is felt by the infected person) of both conditions.

It’s important to consider symptoms in the right context: how soon they developed, what preceded them, how they’re evolving over time, etc.

Similarities of herpes and primary syphilis symptoms	Differences between herpes and primary syphilis signs
Both conditions may have systemic symptoms: overall weakness, fever, enlarged lymph nodes, muscle aches, and loss of appetite	Pain Herpes blisters and sores are tingly, itchy, and painful in different stages. Syphilis sores are painless.

Table 2. Similarities of and differences between the common signs of herpes (what the patient and doctor see)

In the table below, we summarize the common signs of both conditions. Signs are more reliable than symptoms when it comes to establishing a diagnosis. They’re objective and can be seen by the patient and the doctor.

Similarities of herpes and primary syphilis signs	Differences between herpes and primary syphilis signs
Location Both conditions can affect the vagina, penis, anus, or mouth. Can ulcerate Both conditions can present as an ulcer (a concave sore).	Incubation period (timing of the sores’ appearance) Syphilis About three weeks after the initial infection Herpes Two to four days after exposure Multiple vs. singular Herpes Multiple painful blisters or multiple painful sores depending on timing Syphilis Usually, a single lesion Appearance of sores Syphilis Single sore Up to 3 cm in diameter Deep, painless, and hard when felt Herpes Multiple blisters and sores Small size (1–3 mm in diameter); clustered together Superficial—affects only the top layer of the skin; no firmness felt when pinched Pain Herpes Painful Syphilis Painless Duration of skin symptoms Syphilis Up to 8 weeks Heals with scarring Herpes Two to four weeks Heals without scarring

Similarities of herpes and
primary syphilis signs

Differences between herpes
and primary syphilis signs

Location

Both conditions can affect the vagina, penis, anus, or mouth.

Can ulcerate

Both conditions can present as an ulcer (a concave sore).

Incubation period (timing of the sores’ appearance)

Syphilis

About three weeks after the initial infection

Herpes

Two to four days after exposure

Multiple vs. singular

Herpes

Multiple painful blisters or multiple painful sores depending on timing

Syphilis

Usually, a single lesion

Appearance of sores

Syphilis

Single sore
Up to 3 cm in diameter
Deep, painless, and hard when felt

Herpes

Multiple blisters and sores
Small size (1–3 mm in diameter); clustered together
Superficial—affects only the top layer of the skin; no firmness felt when pinched

Pain

Herpes
- Painful
Syphilis
- Painless

Duration of skin symptoms

Syphilis

Up to 8 weeks
Heals with scarring

Herpes

Two to four weeks
Heals without scarring

Side-by-side photos of herpes and syphilis

These pictures show the differences between the superficial sores of herpes and the sores of primary syphilis.

Pay special attention to the following:

Herpes sores present as multiple clustered sores, while syphilis usually presents with one sore.
Herpes sores are small; syphilis sore are much bigger.
Herpes sores are very superficial (on the surface of the skin), but a syphilis sore is deep (firm when touched, with underlying firmness of the skin).
With herpes sores, their base is crusted; a syphilis sore has a clean base.
A syphilis sore’s border is hard to the touch and well defined, unlike herpes sores.

Herpes

Image source: https://www.webmd.com/genital-herpes/ss/slideshow-genital-herpes

Syphilis

Image source: https://nunatsiaq.com/stories/article/65674nunavut_health_officials_say_syphilis_is_on_the_rise/

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Frequently Asked Questions

In this frequently asked questions section, Dr. Fuzayloff answers in more detail questions about the most important points that differentiate between the two conditions.

How can a doctor tell the difference between herpes and syphilis?
When a doctor examines a person with suspected herpes or syphilis, they try to put the signs and symptoms into the right context.

What is the right context? It’s the history of the disease: what preceded the signs and symptoms, when they began appearing, how they’re evolving, and whether there are other associated symptoms.
The time that’s passed since a risky encounter
This is a very important point that distinguishes herpes from syphilis. Herpes blisters appear two to four days after the initial exposure. A syphilis sore, on the other hand, may take three or four weeks after exposure to appear.
The number of sores
Syphilis usually presents with solitary sore; very rarely, there are two to four lesions. The herpes infection presents as multiple lesions that usually are clustered and share a red base.
The appearance of the sores
To visually distinguish syphilis lesions from herpes lesions, follow the rule of three S’s:

Surface
- Syphilis lesions usually have a rough, clean surface and are not filled with fluid. Herpes lesions are very superficial blister (fluid-filled sacs) or crusted sores, depending on the stage.
Shape
- Syphilis lesions are usually round with indurated (hard) raised borders. Herpes lesions are very superficial and not felt with touch (there’s no underlying hardness of the skin).
Size
- Syphilis lesions are up to 3 cm in diameter. Herpes lesions are only 2–3 mm in diameter.
Associated pain
Unlike herpes lesions, a primary syphilis sore is not painful or itchy (that’s why it goes unnoticed).
Duration of skin symptoms
Syphilis has a longer incubation period and it’s longer before a syphilis sore becomes visible. And it lasts longer after it appears.

With syphilis, the lesion might take up to two weeks to become visible and up to 8 weeks to heal. It might scar after healing since the lesion penetrates the entire skin thickness.

Herpes lesions might take one or two days to appear and on average last for two weeks (this might extend to four weeks in the first outbreak). Since the lesions are superficial, no scarring is expected after healing.

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Herpes vs. syphilis (primary stage)

Table 1. Similarities of and differences between these conditions’ common symptoms (what the patient feels)

Table 2. Similarities of and differences between the common signs of herpes (what the patient and doctor see)

Side-by-side photos of herpes and syphilis

Frequently Asked Questions

How can a doctor tell the difference between herpes and syphilis?

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