Fungal infection or STI? Distinguishing signs and symptoms correctly

Fungal infections and sexually transmitted infections (STIs) are among the most common health complaints in the genital area. In Germany, more than 8.4 million people—over 10% of the population—are affected by fungal infections (Ärzteblatt, 2019). Both can cause similar symptoms such as itching, redness, or discharge, but require different treatments. This blog discusses the key differences and similarities between fungal infections and STIs, highlights typical symptoms, explains diagnostic options, and provides an overview of treatment possibilities. 

Table of Contents

• What is a fungal infection?
• What are sexually transmitted infections (STIs)?
• Symptoms: Fungal infection vs. STI
• How are fungal infections and STIs diagnosed?
• How are STIs treated?
• How are fungal infections treated?
• How can fungal infections be prevented?
• Overview: Key prevention measures for STIs
• Summary

What is a fungal infection?

A fungal infection, also called mycosis, can affect the skin, nails, mucous membranes, or internal organs. It commonly occurs in the genital area, where fungi can thrive in warm and moist conditions. The most frequent cause is an overgrowth of the yeast Candida albicans, which naturally exists in the body. An imbalance in the body’s natural defense system—caused by antibiotics, hormonal changes (pregnancy, menopause), or diabetes mellitus—can promote this overgrowth. Other causes include inadequate or excessive intimate hygiene, damp clothing, or tight clothes that promote fungal growth (CDC, 2024).

Are fungal infections contagious?

Fungal infections such as Candida infections are generally not highly contagious but can be transmitted under certain conditions. Transmission depends on the type of fungus, the condition of the skin or mucous membranes, and the recipient’s immune response. Close contact, irritated skin, and warm, moist environments increase the risk of transmission.

What are sexually transmitted infections (STIs)?

Sexually transmitted infections (STIs) are infections primarily transmitted through unprotected sexual contact. Common pathogens include bacteria such as those responsible for chlamydia, gonorrhoea, and syphilis, and viruses like HIV, herpes simplex virus (HSV), and human papillomavirus (HPV). Parasites, such as in trichomoniasis, can also be transmitted. STIs are spread through:

• Vaginal, oral, and anal intercourse
• Direct skin-to-skin contact
• Contact with infected mucous membranes or body fluids such as semen, vaginal secretions, and blood
• Use of contaminated sex toys without thorough cleaning
• In rare cases, through shared needles, blood transfusions, or from mother to child during birth

Source: Cleveland Clinic, 2023

Symptoms: Fungal Infection vs. STI

Fungal infections and STIs can cause similar symptoms such as redness, swelling, pain, or burning in the genital area, but they also have specific symptoms that help distinguish them. The following table outlines the typical symptoms for each condition:

Sources: MayoClinic, 2024; CDC, 2024; MedlinePlus, 2024

How do I know if I have a fungal infection or an STI?

You can distinguish between a fungal infection and an STI based on symptoms: Fungal infections usually cause intense itching, odorless, whitish-curdlike discharge, and redness. STIs tend to cause foul-smelling, colored discharge, skin changes such as blisters or sores, and sometimes fever or swollen lymph nodes. However, STIs can often be asymptomatic, which is why regular STI testing is important, especially if you have multiple sexual partners or engage in unprotected sex.

Which STIs can be mistaken for fungal infections?

Trichomoniasis, genital herpes, chlamydia, and gonorrhoea are particularly likely to be mistaken for fungal infections, as they often cause itching.

When should you see a doctor?

A doctor’s visit is advisable to clarify the cause of the symptoms and initiate appropriate treatment. You should consult a healthcare provider especially if:

• Symptoms persist for more than a few days or worsen (e.g., itching, pain, unusual discharge)
• Skin changes such as blisters, warts, or sores appear
• You are unsure whether it’s a fungal infection or an STI
• Symptoms occur after unprotected sex or there is an increased risk of infection

Sources: MayoClinic, 2024; MedlinePlus, 2024

How are fungal infections and STIs diagnosed?

Fungal infections are usually diagnosed through a clinical examination of the symptoms. To confirm, skin or mucosal swabs can be examined microscopically or cultured.

STIs are diagnosed based on medical history, physical examination, and laboratory tests. These include swabs from affected areas as well as blood and urine tests. In Germany, these tests can be performed by general practitioners, gynecologists, urologists, or public health authorities. In addition, home tests are available that can be conducted discreetly at home.

Source: CDC, 2024

IMPORTANT: If diagnosed with an STI, it is essential to inform your sexual partner(s), as they may also be infected. Only testing and, if necessary, treatment can protect them and prevent further spread. Open communication is key to protecting everyone’s health.

How are STIs treated?

STI treatment depends on the pathogen and the severity of the infection. Bacterial infections like chlamydia, gonorrhoea, or syphilis are effectively treated with antibiotics. Parasitic infections like trichomoniasis respond well to antiparasitic medication. Viral infections such as herpes or HIV cannot be completely cured, as the viruses remain in the body. However, medications like acyclovir (for herpes) or antiretroviral therapy (for HIV) relieve symptoms, suppress viral replication, and reduce transmission risk (WHO, 2024).

It is important to complete the treatment exactly as prescribed by the doctor, even if symptoms have subsided, to prevent relapses and resistance.

How are fungal infections treated?

Fungal infections are usually treated with antifungal medications that inhibit or kill fungal growth. These can be applied as creams, vaginal suppositories, tablets, or ointments, depending on the affected body area (CDC, 2024).

What helps quickly against fungal infections?

In addition to medication, the following measures can support the healing of a fungal infection:

• Breathable clothing: Wear cotton underwear and avoid tight, synthetic clothing
• Hygiene: Use mild, pH-neutral products and keep the genital area dry
• Diet: Follow a low-sugar diet, as sugar can promote fungal growth
• Natural remedies: Sitz baths with chamomile or tea tree oil, but only after consulting a doctor

How can fungal infections be prevented?

In addition to medication, many of the measures that support healing also help prevent fungal infections, such as wearing breathable clothing or using mild hygiene products. A strong immune system—through adequate sleep, stress reduction, and a balanced diet—is also essential to prevent fungal infections in the long term (CDC, 2024).

Overview: Key Prevention Measures for STIs

The most important prevention strategies for STIs help reduce the risk of infection and protect both your own health and that of others. The following chart summarizes the main measures for preventing sexually transmitted infections:

Sources: Own illustration based on NHS, 2024

Summary

Fungal infections are conditions caused by fungi such as Candida albicans, often leading to itching, redness, and odorless discharge. Sexually transmitted infections (STIs) are caused by bacteria, viruses, or parasites and are transmitted through close contact or sexual intercourse. They can cause symptoms such as unusual discharge, skin changes, or fever. Both conditions can cause similar symptoms in the genital area, which can lead to confusion. Testing is essential to make the correct diagnosis, initiate appropriate treatment, and prevent further infections through prevention strategies.