Adolescence can be a time of great change and growth as teenagers start to assert their independence and navigate the complexities of adulthood.

However, this period of transformation can also leave teenagers susceptible to a range of illnesses and health issues. Here are 43 diseases that commonly occur during adolescence.

1. Acne

Acne is a common skin condition that affects many teenagers. It occurs when hair follicles become clogged with oil and dead skin cells, leading to the formation of pimples, blackheads, and whiteheads.

2. Allergies

Allergies occur when the body’s immune system overreacts to a substance that is usually harmless. Common allergens include pollen, dust mites, and certain foods.

3. Anxiety Disorders

Many teenagers experience anxiety, which can be a normal response to stress. However, some teens may develop anxiety disorders, which can interfere with daily activities and require treatment.

4. Asthma

Asthma is a chronic respiratory condition that can make it difficult to breathe. It is commonly triggered by exercise, allergies, and respiratory infections.

5. Attention-Deficit/Hyperactivity Disorder (ADHD)

ADHD is a neurodevelopmental disorder that affects attention, hyperactivity, and impulsivity. It can make it difficult for teenagers to focus in school and complete assignments.

6. Bipolar Disorder

Bipolar disorder is a mood disorder that causes extreme changes in emotions, energy, and behavior. Symptoms can range from manic episodes of extreme happiness and excitement to depressive episodes of sadness and hopelessness.

7. Bulimia

Bulimia is an eating disorder that involves binge eating followed by purging through vomiting or laxative use. It can lead to a range of health problems, including electrolyte imbalances and dental issues.

8. Chlamydia

Chlamydia is a sexually transmitted infection (STI) that can cause no symptoms or mild symptoms like discharge or burning during urination. If untreated, it can lead to serious health problems like infertility.

9. Depression

Depression is a mood disorder that causes persistent feelings of sadness, hopelessness, and worthlessness. It can affect the way teenagers think, feel, and behave.

10. Diabetes

Diabetes is a chronic condition that occurs when the body is unable to properly regulate blood sugar levels. Type 1 diabetes is usually diagnosed in childhood or adolescence and requires insulin therapy.

11. Eating Disorders

Teenagers may develop eating disorders like anorexia, bulimia, or binge eating disorder. These disorders can have serious health consequences and require specialized treatment.

12. Eczema

Eczema is a skin condition characterized by itchy, red, and inflamed skin. It can be triggered by certain foods, environmental factors, and stress.

13. Gonorrhea

Gonorrhea is an STI that can cause symptoms like discharge, pain during urination, and bleeding between periods. It can lead to serious complications if left untreated.

14. Gum Disease

Teenagers may develop gum disease if they do not practice good oral hygiene habits. It can cause gum inflammation, bleeding, and tooth loss.

15. Headaches

Many teenagers experience frequent headaches, which can be caused by stress, lack of sleep, or other factors. If headaches become severe or frequent, medical attention may be necessary.

16. Hepatitis

Hepatitis is a viral infection that can cause liver damage. It can be transmitted through unprotected sex, injection drug use, or other forms of contact with infected blood or bodily fluids.

17. Herpes

Herpes is an STI caused by the herpes simplex virus. It can cause painful blisters or sores around the mouth or genitals.

18. HIV/AIDS

HIV is a virus that attacks the immune system, making it difficult for the body to fight off infections. If left untreated, HIV can progress to AIDS, a condition that can be fatal.

19. Human Papillomavirus (HPV)

HPV is a common sexually transmitted infection that can cause genital warts. Certain strains of HPV can also cause cancer.

20. Influenza

Influenza, or the flu, is a contagious respiratory illness that can cause fever, cough, and body aches. It can be prevented through an annual flu vaccine.

21. Irritable Bowel Syndrome (IBS)

IBS is a functional gastrointestinal disorder that can cause abdominal pain, bloating, and changes in bowel habits. It is often triggered by stress or certain foods.

22. Meningitis

Meningitis is a serious infection that affects the membranes surrounding the brain and spinal cord. It can cause symptoms like fever, headache, and neck stiffness, and can be fatal.

23. Mononucleosis

Mononucleosis, or “mono,” is a viral infection that can cause fatigue, fever, and sore throat. It is commonly spread through saliva and can be prevented through good hygiene practices.

24. Obesity

Obesity, or being severely overweight, can lead to a range of health problems like high blood pressure, diabetes, and heart disease. It is often caused by a combination of genetics and lifestyle factors.

25. Osteoporosis

Osteoporosis is a condition characterized by weak and brittle bones. It can be prevented through proper nutrition and regular exercise.

26. Panic Disorder

Panic disorder is a type of anxiety disorder that causes intense, recurrent episodes of fear and panic. It can be triggered by different situations and can interfere with daily functioning.

27. Pelvic Inflammatory Disease (PID)

PID is an infection of the reproductive organs that can cause symptoms like abdominal pain, fever, and vaginal discharge. It can lead to serious complications like infertility if left untreated.

28. Periodontitis

Periodontitis is a more serious form of gum disease that can cause bone loss and tooth loss. It is often caused by poor dental hygiene.

29. Polycystic Ovary Syndrome (PCOS)

PCOS is a hormonal disorder that can cause irregular periods, acne, and weight gain. It can increase the risk of developing diabetes and other health problems.

30. Post-Traumatic Stress Disorder (PTSD)

PTSD is a mental health condition that can develop after experiencing a traumatic event. It can cause symptoms like flashbacks, nightmares, and avoidance behavior.

31. Substance Abuse

Teenagers may experiment with drugs or alcohol, which can lead to addiction and other health problems. Substance abuse can also have serious social and legal consequences.

32. Schizophrenia

Schizophrenia is a mental disorder that can cause delusions, hallucinations, and disordered thinking. It usually develops in late adolescence or early adulthood.

33. Sleep Disorders

Many teenagers experience sleep disturbances like insomnia or sleep apnea, which can interfere with daily functioning. Good sleep habits and medical treatment can help alleviate symptoms.

Smoking can cause a range of health problems like lung cancer, heart disease, and respiratory infections. Teenagers who smoke or are exposed to secondhand smoke are at increased risk.

35. Strep Throat

Strep throat is a bacterial infection that causes sore throat, fever, and difficulty swallowing. It can be treated with antibiotics.

36. Substance Withdrawal

Teenagers who become addicted to drugs or alcohol may experience withdrawal symptoms like nausea, sweating, and anxiety if they try to quit. Medical treatment and support are often necessary for successful recovery.

37. Testicular Cancer

Testicular cancer is a relatively rare form of cancer that affects the testicles. It is most common in young men and can be treated with surgery, radiation, and chemotherapy.

38. Thyroid Disorders

Thyroid disorders like hyperthyroidism and hypothyroidism can cause a range of symptoms like fatigue, weight changes, and mood disturbances. They can be diagnosed through blood tests and treated with medication.

39. Tuberculosis

Tuberculosis (TB) is a bacterial infection that can affect the lungs, lymph nodes, and other parts of the body. It can be treated with antibiotics.

40. Ulcerative Colitis

Ulcerative colitis is a chronic inflammatory bowel disease that can cause abdominal pain, diarrhea, and weight loss. It is treated with medication and sometimes surgery.

41. Urinary Tract Infections (UTIs)

UTIs are bacterial infections that affect the urinary tract. They can cause symptoms like pain during urination, frequent urination, and abdominal pain. They are treated with antibiotics.

42. Varicella (Chickenpox)

Varicella, or chickenpox, is a viral infection characterized by a rash and fever. It is highly contagious but can be prevented through vaccination.

43. Yeast Infections

Yeast infections are fungal infections that can affect the genitals, mouth, and other parts of the body. They can cause symptoms like itching and discharge.