Daily masturbation for one month usually does not cause major health problems. It does not cause weakness, infertility, low testosterone, hair loss, shrinkage of the penis, or permanent sexual dysfunction. Masturbation is considered a normal sexual behavior. Planned Parenthood notes that even daily masturbation can be healthy.

Possible short-term effects, especially if it is rough or repeated several times in a short period, include:

Take a break for a few days and use lubrication if you have soreness. Avoid gripping too tightly or using objects that could injure you. Minor irritation should settle within 1-2 days. Cleveland Clinic describes these as minor, temporary effects rather than serious side effects.

It may be a problem if you cannot control the urge, it is interfering with sleep, work, study, relationships, or you continue despite pain or injury. Seek a clinician or sexual-health/mental-health professional if you have persistent pain, bleeding, discharge, urinary symptoms, a penile curvature or erection injury, or ongoing erectile/orgasm problems.

The medical text Kaplan & Sadock's Comprehensive Textbook of Psychiatry describes masturbation as a normal way to reduce sexual tension in adolescence and notes that historical claims of harm have been rejected (p. 6080-6081).

There is no medical number such as “once daily” or “three times weekly” that defines excessive masturbation.

It is considered excessive when the behavior is hard to control or causes harm, for example:

So, masturbation once a day can be entirely normal if you feel in control, have no injury, and it does not interfere with your life. Even more frequent masturbation is not automatically a disorder. WHO's ICD-11 specifically says that high sexual interest or masturbation alone, including in adolescents, should not be diagnosed as compulsive sexual behavior disorder without significant distress or impairment. WHO ICD-11 criteria

If you have pain, skin damage, persistent difficulty with erections or orgasm, or feel unable to stop despite negative effects, speak with a doctor or mental-health professional. Kaplan & Sadock’s Comprehensive Textbook of Psychiatry notes that ICD-11 recognizes compulsive sexual behavior when sexual behavior becomes life-dominating and harmful, rather than based on frequency alone.