Common STI symptoms in men include unusual discharge from the penis, a burning sensation when urinating, itching, sores or blisters, rashes, and pain or swelling in the testicles. Many sexually transmitted infections cause mild symptoms or none at all, so testing is the only reliable way to know your status.
Why symptoms are an unreliable guide
It is tempting to treat "feeling fine" as a clean bill of health, but that is risky. According to the CDC, many STIs produce no symptoms or only mild ones, so a person can carry and pass on an infection without realizing it. This is part of why STIs spread so widely.
That makes symptom-watching a poor substitute for testing. The sections below describe what can appear, but the absence of these signs does not rule out an infection. If you are sexually active, see our STI testing guide for when and how to get checked.
Discharge from the penis
Unusual discharge from the tip of the penis is one of the most recognizable STI symptoms in men. The fluid may be:
- White, cloudy, or watery (often seen with chlamydia)
- Thick, yellow, or green (often seen with gonorrhea)
- More noticeable first thing in the morning
The NHS lists unusual discharge from the penis as a key reason to visit a sexual health clinic. Discharge is a common feature of chlamydia and gonorrhea, but it can also stem from non-STI causes, so it should always be assessed by a provider.
Pain or burning when urinating
A burning or stinging sensation during urination (dysuria) frequently accompanies discharge. It reflects inflammation of the urethra and is reported with both gonorrhea and chlamydia, per the CDC. You may also feel an urge to urinate more often.
Sores, blisters, warts, and rashes
Skin changes around the genitals, anus, or mouth can signal several infections:
- Painless sores (chancres): A firm, painless ulcer can be the first sign of syphilis. Learn more in our overview of syphilis.
- Painful blisters or ulcers: Clusters of small, painful blisters point toward genital herpes.
- Lumps or warts: Soft, flesh-colored growths can be caused by HPV.
- Rashes: A rash on the palms, soles, or trunk can appear in later-stage syphilis.
Because these lesions can look similar to harmless skin conditions, a provider should examine any new sore, bump, or rash in the genital area.
Itching, irritation, and testicular pain
Other symptoms men may notice include:
- Itching, tingling, or irritation around the penis, testicles, or anus
- Redness or soreness at the tip of the penis
- Pain or swelling in one or both testicles
Testicular pain or swelling is less common but important, as it can signal that an infection such as chlamydia or gonorrhea has spread to the epididymis (the tube behind the testicle). The CDC notes this can occur with chlamydia, though it is uncommon. Sudden, severe testicular pain needs prompt medical attention.
Symptoms from oral or anal sex
STIs are not limited to the genitals. Infections acquired through other types of sex can cause:
- A sore throat or throat infection
- Anal discomfort, discharge, or pain during bowel movements
These signs are easy to overlook. Our article on whether you can get an STI from oral sex explains how non-genital infections happen and why testing the relevant sites matters.
How long symptoms take to appear
Timing varies widely. Some symptoms emerge within a few days of exposure, while others take weeks, and many infections never produce noticeable signs. This delay is why providers often recommend waiting a set period before testing after a possible exposure. For specifics, see how long STIs take to show up.
When to see a healthcare provider
See a healthcare provider or sexual health clinic if you notice any of the following, or if a partner tells you they have an STI:
- Discharge from the penis
- Pain or burning when urinating
- Sores, blisters, warts, or a rash in the genital or anal area
- Testicular pain or swelling
- Itching or persistent irritation
You should also get tested after unprotected sex even if you feel completely well. For prevention strategies, see how to prevent STIs. This article is general education and is not a substitute for individualized medical advice. To understand the full topic, visit our STIs and testing hub.
The bottom line
STI symptoms in men most often involve penile discharge, painful urination, sores or blisters, rashes, and testicular pain, but a large share of infections cause no symptoms at all. Because you cannot rely on how you feel, regular testing is the only way to know your status and protect your partners. If you notice any of these signs, or have had a possible exposure, talk with a healthcare provider. For comparison, you can also read about STI symptoms in women.
