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STI vs. STD: What’s the Difference?

Medically Approved by Dr. Edward Salko

Table of Contents

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Sexually transmitted infections (STI) and sexually transmitted diseases (STD) are considered similar and used interchangeably. However, contrary to popular belief, STIs and STDs are not the same. 

Generally, STIs refer to the entry of disease-causing germs or pathogens such as bacteria, viruses, and parasites into the body through sexual activities. On the other hand, STDs can develop after the infection has occurred. 

According to WHO, more than 1 million individuals acquire STIs every day worldwide, and most of the population retains the infection without developing STDs. This means that they are asymptomatic but carriers of the causative agents.

Therefore, without understanding the true meaning behind STI vs. STD, you could infect your sexual partner or develop complications due to untreated STIs. 

In the next few lines, you’ll learn how to tell the difference and what tests you need to take. 

STI vs. STD: Is There Really a Difference? 

The main difference between an STI and STD is the stage wherein they occur. Both conditions entail the presence of pathogens, but the primary difference between STI and STD is the manifestation of symptoms. 

Infection happens when bacteria, viruses, or a parasite enters your body, starts to multiply, and destroys your cells. 

Meanwhile, a disease may develop from an infection in your damaged cells. Additionally, clear signs and symptoms of the illness appear when you have the disease and not necessarily the infection.

Generally, the development of symptoms results from your immune system’s response to the infection. white blood cells, like antibodies, are produced to fight against the invading microorganisms or substances

For example, when you experience a mild fever, this is your body working to get rid of the virus or bacteria in your body. 

Moreover, asymptomatic STIs are called a hidden epidemic. This is because many people who have STIs are not aware that they are infected due to a lack of symptoms. Thus, it is highly recommended to have yourself checked to treat and mitigate the spread of the infection. 

Common STDs and Symptoms to Watch Out For

According to CDC’s report, in 2021, 1 out of 5 people in the US will have a sexually transmitted disease. Here are the eight common STDs to watch out for:

  1. Chlamydia

It is a bacterial infection in your genitals acquired through unsafe anal, oral, or vaginal intercourse. Moreover, women with Chlamydia may experience discharge from the genitals or anus, pain in the lower belly, and fever.

However, this may not be detected right away in the early stage of infection due to a lack of signs and symptoms. For women, this can result in infertility if left untreated.

You can take a blood test for Chlamydia to know if you have contracted the infection.

  1. Genital herpes

It is passed through nonsexual contact, but it can be spread by oral sex. Some people experience red bumps, blisters, or sore outbreaks in the genitals or anus triggered by stress, illness, overfatigue, or when periods happen. Also, it is a common type of STD that is usually overlooked.

With that being said, you can take a Genital Herpes Blood Test, which detects exposure to Herpes Simplex Virus (HSV), to avoid further discomfort.

  1. Gonorrhea

It is also a bacterial infection in the genital tract and can grow in your mouth, eye, and anus.

With gonorrhea, you may experience discharge from the genitals, and anus, pain in testicles for men, vaginal bleeding between periods for women, pain in the lower belly and when peeing, and rectal pain, especially when pooping.

Moreover, symptoms of gonorrhea may appear within ten days, but some people who are infected only notice the signs and symptoms after a few months.

If you had unprotected sex recently and think you may have contracted STD, you can take a Comprehensive STD Blood test right away to help you treat and mitigate the transmission of the infection.

  1. HIV and AIDS

These are acquired through sexual intercourse, but they could also come from bodily fluids that have viruses and bacteria.

The human immunodeficiency virus (HIV) attacks your immune system. Consequently, your immune system becomes weaker, and your body is less resilient in fighting off infections.

Moreover, Acquired Immune Deficiency Syndrome happens when you have had HIV for a long time and your immune system is severely weak to fight off infections anymore.

You can experience headache, rash, fever, swollen glands, muscle and joint pain, diarrhea, painful ulcers in the mouth or around the penis, anus, weight loss, and a severe number of infections. The latter happens in extreme cases.

Thus, if you have unprotected sex or may have shared a needle with someone, you can take HIV Screening Test (4th Generation). It is a type of blood test which detects acute HIV infection  4-12 days earlier.

  1. Hepatitis B Virus (HBV)

It is a liver infection that can cause liver cancer. People can get infected with HBV because of unprotected sex with a person who has the disease.

Moreover, a person who has an HBV infection may experience fatigue, appetite loss, having a mild fever, the feeling of vomiting or throwing up, darker pee, yellowish skin, eyes, and belly pain.

If you suspect that you have HBV, you can try the Hepatitis B antigen Blood Test. This test is used to help diagnose Hepatitis B Virus (HBV) infections.

  1. Pelvic Inflammatory Disease (PID)

It is an infection of the ovaries, uterus, or fallopian tube. These symptoms are painful peeing, vaginal discharge, and irregular periods or spotting. 

This is often caused by chlamydia or gonorrhea. Moreover, infertility is a major complication one can have with PID.

Thus, taking a blood test for PID helps diagnose infections or diseases that cause inflammation and allows immediate treatment.

  1. Syphilis

Syphilis is transmitted through sexual intercourse that causes symptoms of soreness on your rectum, genitals, or mouth. It can lead to serious health complications if not treated. 

Additionally, it increases the risk of HIV infection. For women, it can cause complications during pregnancy.

If you think you have sexual contact with a partner with syphilis or multiple partners and do not practice safe sex, you can take Syphilis Blood Test

This test is used to screen Treponema Pallidum bacteria that causes the infection.

  1. Trichomoniasis

This is a common STI caused by a parasite called Trichomonas vaginalis. It is spread through vaginal sex. Men and women who have unprotected sex and more than one sexual partner are prone to trich. 

Many people with trichomoniasis experience symptoms like smelly vaginal and penis discharge along with itching or irritation inside the penis, redness, tenderness in the vagina, pain when peeing or during sex, and bleeding after sex.

With that being said, there are two different blood tests for females and males to test the Trichomonas vaginalis—a parasite that is one of the most commonly transmitted infections in the U.S.

Health Consequences of Untreated STIs and STDs 

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According to a report, STDs will become a sweeping epidemic in the United States in 2021. That is to say, the percentages of STDs have skyrocketed again for the sixth year.

Furthermore, CDC said that nearly 2.5 million people in America had been infected with chlamydia, syphilis, and gonorrhea in 2019.

With that being said, there are several health consequences of untreated STIs and STDs, and some of them are detrimental to your quality of life. 


According to CDC, STDs impact women and men differently.


Men with STDs experience pain or burning during urination, frequent urination, pain during ejaculation, bumps, blisters, sores, or abnormal colored or foul-smelling discharge from the penis.

In addition, HIV and HPV are common in men that can lead to cancer of the penis and anus if left untreated.


Women with untreated STDs can lead to serious health complications such as pelvic inflammatory disease, resulting in ectopic pregnancy and infertility.

Also, pregnant women with STDs such as Syphilis, genital herpes, and HIV can pass these diseases to their babies during pregnancy or delivery.

Complications of STDs in babies may include low birth weight, stillbirth, blindness, deafness, and brain damage. More importantly, HPV is the most common STI in women that causes cervical cancer.

How long do symptoms appear after STI incubation? 

When you contract a sexually transmitted infection, your body undergoes incubation for seven days to several weeks. The incubation period varies depending on what kind of infection you have. 

Common STDs such as chlamydia, genital herpes, warts, gonorrhea, syphilis, or HIV can have clear signs of symptoms in as early as one week or up to 6 weeks.

During the incubation period, your body recognizes the pathogens or disease-causing agents. 

Then, your body produces white blood cells and antibodies to fight off any infection in your body. Also, you may not experience any symptoms during this period.

How to Get Tested for STI and STD? 

  • Order an STD test online: If you want more accurate STD testing, go for an online lab testing where you can easily book the test through your account, take the test to the nearest laboratory, and get the results discreetly. 

Compared to self-performed tests, STD blood tests aided by a lab technician get more accurate results due to reduced human error.  

  • Go to your local health clinics. There are government-funded local clinics that perform free or inexpensive STI tests for gonorrhea, syphilis, chlamydia, and HIV.
  • Go and see your doctor. Seeking professional help is one way to treat your condition.  With that being said, the doctor may give you specific STIs tests after checking up. 

For instance, with other cases of HPV, men are diagnosed by visual inspection or biopsy of genital warts. In comparison, women undergo HPV and Pap tests to check the abnormal cells in the cervix.

Bottom Line 

Understanding STI vs. STD in the context of symptom development can be a good start to spreading the importance of regular STD testing. 

Engaging in safe sex and getting yourself and your partner checked and tested occasionally is one of the ways to prevent contracting infections and developing diseases.

Also, if you are experiencing some of the symptoms mentioned above, do not be embarrassed to see your doctor. Consequently, seeking professional medical help is an advantage you should take from the get-go.

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